Biochemistry

Question 1

what is the effect of histone ubiquitylation?

Answer 1

affects chromatin structure and gene transcription . effects chromosome alignment and segregation. DNA repair, transcriptional response to inflammation

Question 2

how does telomerase function to solve the end replication dilemma?

Answer 2

contains telomeric RNA which allows it to extend the 3’ end of DNA

Question 3

NADPH is an important reductant in the ….pathway

Answer 3

pentose phosphate pathway

Question 4

DNA structure is referred to as what?

Answer 4

double helix

Question 5

what does each enzyme in DNA replication do. Helicase, topoisomerase, primase, ligase, DNA polymerase 3 and DNA polymerase 1?

Answer 5

helicase - unwinds DNA
topoisomerase - nicks backbone and releases tension that results from strand separation.
Primase- lays down RNA primer. leading strand needs just one but for the lagging strand each Okazaki fragment needs one
DNA polymerase 3- elongates nucleotide chain from the RNA primers. 3-5’ exonuclease activity
DNA polymerase 1 - this has the job of removing RNA primers and replacing with DNA. enzyme has 5’-3’ exonuclease activity.
Ligase seals Nick in the backbone to join two Okazaki fragments

Question 6

peptide bonds of alpha helices are aligned … to the helical axis

Answer 6

parallel

Question 7

signals for cells to activate anabolic pathways

Answer 7

high NADH, high NADPH, high ATP

Question 8

what repair pathway is used when there is an insertion or deletion in the DNA?

Answer 8

Mismatch repair pathway

Question 9

what three amino acids can undergo phosphorylation.

Answer 9

those that contain -OH. Serine, threonine, and tyrosine

Question 10

double bonds in naturally occurring double bonds are in the … configuration

Answer 10

cis

Question 11

what role can protein phosphorylation have ?

Answer 11

change the affinity of a protein to a ligand or substrate. also can be a docking site for proteins

Question 12

tRNA is an … molecule between mRNA and amino acids

Answer 12

adaptor

Question 13

where is sphingomyelin abundant ?

Answer 13

nerve cells for transmission of impulse (action potential)

Question 14

CAAT, GC and TATA are common elements of the…. of a gene? they are consensus sequences often found in the … ?

Answer 14

core promoter. these are regulatory sequences

Question 15

GPLs are a major component of the …?

Answer 15

cell memrbrane

Question 16

what is the property of DNA polymerase that makes it self correcting ?

Answer 16

3-5’ exonuclease activity. Can cleave off mis matched base pair

Question 17

how many Hydrogen bonds does A T form vs C

Answer 17

2 and 3, respectively

Question 18

strands in DNA are arranged in a … fashion?

Answer 18

antiparallel

Question 19

what are the 3 non polar amino acids that contain an aromatic ring? what are their one letter codes

Answer 19

phenylalanine (F), tyrosine (Y), tryptophan (W)

Question 20

mRNA binding site of the ribosome located in the …?

Answer 20

small subunit

Question 21

what family of proteins is ubiquitinated and degraded as a result of the stage of the cell cycle

Answer 21

cyclins. different cyclins expressed at various stages of the cell cycle. certain cyclin is present at G1 and then is degraded as the cell moves into S phase. ensures correct progression through the cell cycle

Question 22

what are the 7 roles of proteins?

Answer 22

transport - hemoglobin, contraction - actin, structural - collagen, hormones - TSH, enzymes, control of transcription and translation - polymerase, ribosomes, transcription factors, protection - immunoglobulins

Question 23

how is pre-insulin modified to become mature insulin ?

Answer 23

disulphide bonds form between A and B chains. C or connecting peptide chain between A and B chains is removed

Question 24

omega carbon is??

Answer 24

carbon furthest away from the carboxyl group

Question 25

main role of triacylglycerols?

Answer 25

energy storage in adipose tissue

Question 26

300 nm fibres are compressed and fold to form a ?

Answer 26

250 nm wide fibre

Question 27

alpha helices have … residues per turn? are turn which way

Answer 27

3.6. right handed

Question 28

why is a peptide bond planar ?

Answer 28

resonance of the amide bond. Partial bond between C of 1 residue with the N of the other residue

Question 29

with the lagging strand we get … synthesis, while with eh leading strand we get … synthesis. short segments made during lagging strand synthesis are referred to as..

Answer 29

discontinuous. continuous. Okazaki fragments. we get discontinuous synthesis of the lagging strand because the replication fork is moving in the opposition direction of synthesis. DNA is only synthesized 5-3’

Question 30

ATP can be formed via which 2 processes?

Answer 30

substrate level phosphorylation
oxidative phosphorylation

Question 31

3’ poly a tail has the role of …?

Answer 31

controlling the stability of mRNA

Question 32

coiling of 250nm wide fibres produces ??

Answer 32

chromatin

Question 33

during replication a new nucleotide is attached to the … of the previous nucleotide?

Answer 33

3’ OH group

Question 34

collagen is rich in what two amino acids ?

Answer 34

glycine and proline

Question 35

what are the 3 stop codons

Answer 35

UAA, UAG,UGA - these do not have an associated amino acid

Question 36

what are the three components of a nucleotide?

Answer 36

deoxyribose sugar, 5’ phosphate group, and 1 of 4 nitrogenous bases

Question 37

RNA - protein complex that has the role of removing introns from RNA transcript?

Answer 37

spliceosome

Question 38

this disorder is within the family of nucleotide excision repair disorders. However there is a specific defect in transcription coupled removal of thymine dimers caused by UV light.

Answer 38

cockayne syndrome

Question 39

name the 5 most common GPLs

Answer 39

phosphatidyl serine, inositol, choline, ethanol amine, glycerol

Question 40

RNA pol2 does what?

Answer 40

synthesizes all mRNA and some non-coding mRNAs

Question 41

what is the main difference between deoxyribose and ribose sugars?

Answer 41

deoxyribose sugar has no 2’ OH group while ribose does

Question 42

… is a protein that is involved in muscle contraction. It is alternatively spliced depending what tissue it is expressed in.

Answer 42

tropomyosin

Question 43

lipids having non polar and polar properties are termed ?

Answer 43

amphipathic

Question 44

single stranded region of the tRNA at the 3’ end has what functional role?

Answer 44

attaches to amino acid

Question 45

Inactive/ condensed chromatin. Not exposed so hard for transcription factors to bind

Answer 45

heterochromatin

Question 46

3’ end of DNA contains what?

Answer 46

hydroxyl group (-OH)

Question 47

…. is required for the complete oxidation of fuel molecules and thus maximum energy extraction

Answer 47

oxygen

Question 48

during translation the … moves 1 codon towards the 3’ end of the mRNA before the…

Answer 48

large subunit. small subunit

Question 49

describe structure of DAG

Answer 49

glycerol esterified to two FAs

Question 50

mode of action of imatinib?

Answer 50

ATP competitive inhibitor. Inhibits Bar-abl kinase capacity

Question 51

which two aminos acids act as strong helix breakers.

Answer 51

proline - rigidity glycine - small R group supports other conformations

Question 52

template strand is also called what?

Answer 52

antisense strand, non-coding

Question 53

region spliced out during processing of primary mRNA?

Answer 53

intron

Question 54

3 ways to control gene expression

Answer 54

chromatin remodelling, availability of transcription factors, stability of mRNA

Question 55

what is quaternary protein?

Answer 55

two or more polypeptide chains binding together. can be covalent or non covalent

Question 56

when ribosome encounters a stop codon in the A site, a … factor will bind this site and lead to disassociation of both ribosomal subunits from the mRNA and release of polypeptide chain

Answer 56

release factor

Question 57

what are the two classes of protein?

Answer 57

fibrous (eg collagen) - these typically have one secondary structure. globular - mixter of secondary structures.

Question 58

most naturally occurring Fatty acids have a .. number of carbons

Answer 58

even

Question 59

clusters of ribosomes may sit on a mRNA transcript each actively transcribing a polypeptide. This is termed what?

Answer 59

polyribosome

Question 60

genes beside housekeeping genes have regulated expression. expression can be 1,2,3 specific

Answer 60

tissue, temporal and developmental specific

Question 61

biotin is linked to some enzymes via linkage to what amino acid?

Answer 61

lysine

Question 62

miRNA binding to 3’ UTR of target mRNA can lead to …?

Answer 62

mRNA degradation and/or reduce translation

Question 63

tRNA binds … to the mRNA codon?

Answer 63

antiparallel

Question 64

these two disorder are characterized by defects in DNA damage response?

Answer 64

ataxiatelangiectasic and Li Fraumeni syndrome

Question 65

DNA is always read ….?

Answer 65

5-3’

Question 66

for the poly A tail to be added, the mRNA must first be … in the 3’ UTR

Answer 66

cleaved

Question 67

What is the bond that holds adjacent nucleotides together?

Answer 67

3-5’ phosphodiester bond

Question 68

the … ring of NAD+ accepts … electrons and 1 … in going to the reduced state ….

Answer 68

nicotinamide
2 electrons
1 proton
NADH

Question 69

R groups in beta sheets protrude from the sheet in .. and .. direction

Answer 69

up and down

Question 70

True or False. all protein products within the mitochondria are encoded by the nuclear genome?

Answer 70

False. The mitochondria has its own circular genome with 37 genes

Question 71

growing peptide chain grows from the .. to the.. terminus ?

Answer 71

N to C

Question 72

cyclooxygenase pathway generates ..?

Answer 72

prostaglandins and thromboxane - role in coagulation and inflammation

Question 73

the mRNA transcript is translated in the … direction ??

Answer 73

5-3’ direction

Question 74

how do cis bonds affect structure of lipid aggregates?

Answer 74

bend and pack in a less ordered way

Question 75

histone proteins are … charged and DNA is … charged?

Answer 75

positive and negative, respectively

Question 76

tRNA can have unusual bases, including … this base cannot base pair with …

Answer 76

inosine. G but can base pair with A, U, C

Question 77

general structure of cholesterol?

Answer 77

3 6 membered rings. 1 5 membered ring. OH group given making it somewhat amphipathic. 8 carbon side chain

Question 78

.. Box is found in many genes lacking TATA box (e.g housekeeping genes)

Answer 78

GC

Question 79

linoleic and linolenic acid are the precurors for what? these two molecules are broadly classified as ?

Answer 79

arachidonic acid (ARA) and eicosapentaenoic acid (ERA) 
eicosanoids

Question 80

chromosomes that have the Bcr-abl gene are called what?? what cancers can this lead to

Answer 80

philadelphia chromsome. PC+ acute lymphoblastic leukaemia and chronic myelogenous leukaemia

Question 81

insoluble protein secreted in misfolded state deposits as …?

Answer 81

amyloid

Question 82

transcription occurs in the …?

Answer 82

nucleus

Question 83

AUG is the … codon? and it codes for what amino acid

Answer 83

start. methionine

Question 84

oxidation means what?

Answer 84

loss of electrons. in practice take away electrons from C-H and replace with electrons from O

Question 85

if a …. residue is at the N terminus of a peptide chain it often cyclizes

Answer 85

glutamate

Question 86

what role does cholesterol have on membrane fluidity?

Answer 86

decreases membrane fluidity near the surface but acts as a spacer allowing greater fluidity deeper inside the lipid bilayer

Question 87

… collagen chains come together to form a .. handed superhelical triple helix

Answer 87

3. right handed

Question 88

these channels allow for the movement of water across membranes. what organs are they most commonly expressed in

Answer 88

aquaporins
kidneys

Question 89

besides a component of the cell membrane what roles does cholesterol have?

Answer 89

precursor for steroid hormones (estrogen, testosterone, cortisol, calciferol, aldosterone)
also precursor for bile acids and salts (cholic acid and deoxycholic acid)

Question 90

…. with associated translation initiation factors and initiator tRNA moves along the transcript …. to find the first proper start codon (AUG)

Answer 90

small ribosomal subunit. 5’-3’

Question 91

living systems must comply with the ….

Answer 91

laws of thermodynamics

Question 92

structural proteins often have a high proportion of … amino acids?? and repeated … structure ?

Answer 92

hydrophobic. often insoluble . secondary

Question 93

miRNA associates with the complex?

Answer 93

RISC

Question 94

miRNA often binds to the … of mature mRNA and affects?

Answer 94

3’ UTR. mRNA translation and stability

Question 95

these two amino acids are strong alpha helix formers

Answer 95

alanine and leucine

Question 96

what is the isoelectric point?

Answer 96

PH when the overall net surface charge of a polyprotic macromolecule is 0

Question 97

how to enzymes affect reaction kinetics?

Answer 97

they lower the activation energy. usually the bodies thermal energy is sufficient to overcome this.

Question 98

30 nm fibers create loop structures of ??

Answer 98

300 nm

Question 99

name two hemoglobinopathies?

Answer 99

sickle cell anemia and thallasemia

Question 100

… is a general transcription factor that can bind to the Tata box which is 30 nucleotides upstream from transcription start site?

Answer 100

tata binding protein (TBP)

Question 101

what causes van der waal forces?

Answer 101

transient dipole moments within bonds

Question 102

what is a reading frame mutation?

Answer 102

this is an insertion or deletion of nucleotides that is not a multiple of 3. this changes all the codons downstream of the mutation. can have very serious outcome

Question 103

Bcr-abl is a … kinase that is … active. what is the result?

Answer 103

tyrosine kinase that is constitutively active. increased cellular proliferation

Question 104

what are protein domains?

Answer 104

modular units, often with discrete function from which larger proteins are built

Question 105

roles of glycosphingolipids

Answer 105

nerve impulse transmission, cell-cell recognition, molecular recognition

Question 106

what is the structure of sphingomyelin ? is it a glycerophospholipid or a phospholipid

Answer 106

ceramide by phosphorylcholine or ethanolamine esterified to C1 of sphingosine. phospholipid

Question 107

organic solvents disrupt which force that stabilizes protein structure?

Answer 107

hydrophobic interactions

Question 108

general structure of triacylglycerols.

Answer 108

glycerol esterified to 3 fatty acids

Question 109

group disorders characterized by mutations favouring misfolded proteins

Answer 109

amyloidoses

Question 110

what is the structure of hemoglobin? type and number of subunits and associated cofactors

Answer 110

4 subunits. 2 alpha and 2 beta chains. each subunit has a porphyrin molecule which conjuagates iron and is therefore able to bind oxygen

Question 111

TBP after binding to the TATA box recruits … and other accessory TF2 proteins to the promoter. This complex then recruits and phosphorylates … thereby activating it.

Answer 111

TF2D
RNA polymerase

Question 112

heat or cold disrupts what bonds that contribute to protein structure?

Answer 112

hydrophobic interactions and hydrogen bonds

Question 113

a peptide bond is what kind of bond?

Answer 113

amide bond

Question 114

Name 5 types of non-coding RNA and discuss role

Answer 114

rRNA, tRNA, SiRNA, miRNA, snRNA

Question 115

when is base excision repair utilized by the cell?

Answer 115

oxidation of base, introduction of uracil, abasic site, single stranded break

Question 116

RNA pol3 does what?

Answer 116

synthesizes mtRNA

Question 117

what is often found in beta turns

Answer 117

proline in position 2 or glycine in position 3

Question 118

what are 2 essential unsaturated fatty acids ?

Answer 118

linoleic acid (C18:2, omega 6) , linolenic acid (C18:3, omega 3)

Question 119

patients with xeroderma pigmentosum have the inability to resolve …. caused by UV light

Answer 119

thymine dimers

Question 120

the gamma carbon of glutamate can undergo what modification?

Answer 120

gamma carboxyglutamate - now has 2 carboxyl groups. this is important for clotting factors to be able to bind Ca2+

Question 121

endergonic processes can be driven by …. to …. processes

Answer 121

coupling
exergonic

Question 122

define positive cooperativity in regard to oxygen bindin hemoglobin?

Answer 122

once one O2 binds hemoglobin it becomes easier for the 2nd O2 to bind. And this relationship continues

Question 123

non-template strand is also called what?

Answer 123

sense strand or coding

Question 124

what are the 3 amino acids with positively charged R groups and what is their 1 letter code..

Answer 124

lysine (K), arginine (R), Histidine (H)

Question 125

many … reactions are coupled to the exergonic hydrolysis of ATP. The overall free energy change is now

Answer 125

endergonic
negaticve

Question 126

sequence recognized as initiator sequence of translation containing AUG and other consensus sequence is termed ??

Answer 126

Kozaks sequence

Question 127

only … amino acids are found in nature ?

Answer 127

L

Question 128

what is the most common role of ubiquitination ? what amino acid is commonly ubiquitnated ?

Answer 128

target protein for proteosomal degradation. lysine

Question 129

three key energy generation pathways occur in the mitochondria?

Answer 129

beta oxidation, TCA cycle and oxidative phosphorylation

Question 130

the genetic code is termed .. ? multiple codons code for the same amino acid

Answer 130

degenerate

Question 131

virtually all peptide exist in a … configuration?

Answer 131

trans. alpha carbons of adjacent residues are on different sides of the peptide bond

Question 132

what are 2 common secondary protein structures?

Answer 132

alpha helix and beta sheets

Question 133

this element comprises 30-40% of the cell membrane? and what role does it have?

Answer 133

cholesterol
regulates membrane fluidity

Question 134

describe the structure of a typical chromosome?

Answer 134

p arm - this is the short arm (think petite). Q arm - long arm. centromere. telomeres - ends of the chromosome

Question 135

what is the name of the glycosphingolipid that has ceramic conjugated to one of galactose or glucose

Answer 135

cerebroside

Question 136

another word for biosynthesis

Answer 136

anabolism

Question 137

the majority of people with HNPCC have a mutation in what protein?

Answer 137

MLH1

Question 138

what enzyme allows replication of the ends of chromosomes. Is it present in all cells ?

Answer 138

telomerase. no it is not present in every cell. mostly expressed undifferentiated stem cells and cancer cells.

Question 139

why are GC rich regions in DNA harder to separate than AT rich regions?

Answer 139

G base pairing with C contains 1 more hydrogen bond than AT

Question 140

DNA and associated proteins fold and pack the DNA into a more compact structure called ?

Answer 140

chromatin

Question 141

during translation. the … end of the polypeptide chain is uncoupled from the tRNA at the … site and joined by a peptide bond to the free … group of the amino acid linked the tRNA in the A site

Answer 141

carboxyl, P site, amino group

Question 142

what are key proteins in the MMR pathway?

Answer 142

MLH1, MLH2, MSH6 and PMS2

Question 143

if a mismatch in DNA is not correct by DNA polymerase what repair system does the cell utilize to correct it ?

Answer 143

mismatch repair system

Question 144

what is the delta G of exergonic reactions? are they spontaneous

Answer 144

less than 0. Yes

Question 145

what is the fatty acid C18:0

Answer 145

stearic acid

Question 146

antagonistic metabolic pathways are … regulated

Answer 146

co-ordinately regulated. when one is on, the other Is off
- beta oxidation and fatty acid synthesis

Question 147

3 events that take place to form mature mRNA from the primary transcript?

Answer 147

Splicing of introns, add 5’ methylguanosine cap, and 3’ polyadenylation tail (polA tail)

Question 148

what is unique about proline? what consequences does this have when incorporated into a polypeptide

Answer 148

R group forms a cyclic structure with the amino group. this adds rigidity to the structure

Question 149

what are two common motifs in the amino acid sequence of collagen ?

Answer 149

glycine-proline-X.
glycine-X-hydroxyproline

Question 150

why does a small electric dipole exist within the peptide bond?

Answer 150

because of resonance the O has a partial negative charge and the N has a partial positive charge

Question 151

lipooxygenase pathway produces what? and these are important for what?

Answer 151

leukotrienes. inflammatory response

Question 152

glycerophospolipids are derived from which basic compound

Answer 152

phosphatidate. glycerol esterified to 2 fatty acids. 3 carbon is linked to a phosphate group

Question 153

when is base excision repair used? and how can these DNA modification be made

Answer 153

intrastrand crosslink and bulky adducts. UV light and polycyclic aromatic compounds

Question 154

this family of enzymes breaks down GPL

Answer 154

phospholipase

Question 155

this is disorder is characterized by defects in repair of interstrand crosslink. patients have increased pigmentation, abnormalities in the skeleton, heart, kidneys and predisposition to leukaemia ?

Answer 155

Fanconi anemia

Question 156

what are the two properties of DNA polymerase that allow it to replicate DNA with high fidelity ?

Answer 156

highly accurate 5-3’ polymerizing activity
3-5’ exonuclease activity - gives enzyme intrinsic proofreading

Question 157

RNA pol1 does what?

Answer 157

synthesizes rRNA

Question 158

resonance in peptide bond means what?

Answer 158

is less reactive than a ester, quite rigid and planar, exhibit dipole moment in trans configuration

Question 159

estrogen bound to its receptor function as a … and must bind to its …. within the distal promoter

Answer 159

transcription factor. response element

Question 160

because anabolism is endergonic it must be coupled to… for it to be favourable?

Answer 160

ATP hydrolysis

Question 161

are oxidation reactions exergonic or endergonic?

Answer 161

exergonic

Question 162

components of a nucleoside?

Answer 162

sugar + nitrogenous base

Question 163

catabolism is the … of fuel molecules

Answer 163

oxidation

Question 164

what family of proteins is responsible for addition of phosphate group to a protein ? what family removes phosphate groups

Answer 164

kinases
phosphates

Question 165

which class of immunoglobulins is able to cross the placenta ?

Answer 165

IgG

Question 166

hydrolysis of the …. bonds of ATP releases a large amount of energy.

Answer 166

phosphoanhydride

Question 167

transcriptional activators can recruit … which modify residues of the histone N terminal tails which alters chromatin structure

Answer 167

chromatin remodelling complex (histone acetylases)

Question 168

industrial production of unsaturated fatty acids yields C_C double bonds in the … configuration

Answer 168

trans

Question 169

what histone proteins make up the histone core?

Answer 169

H2A, H2B, H3, H4

Question 170

what is the role of splicing ?

Answer 170

to increase the number of proteins from a limited number of genes

Question 171

metabolic pathways must be … favourable??

Answer 171

energetically favourable

Question 172

catabolic and anabolic pathways are distinct allowing both to be … favourable, and … independently

Answer 172

energetically favourable
controlled

Question 173

essential fatty acids have a C-C double bond that is beyond …?

Answer 173

carbon 9

Question 174

what is molecule are most glycosphingolipds derived from ?

Answer 174

ceramide

Question 175

modification of histones and DNA that do not alter the DNA sequence but may alter its ability to be expressed.(alters chromatin structure)

Answer 175

Epigenetic modifications

Question 176

what are 4 important coenzymes that are often required for redox reactions?

Answer 176

NADH, NADPH, FADH2, FMNH2

Question 177

what is the minimum contact distance (van der Waals contact distance )?

Answer 177

distance less than this repulsion is favoured. distance greater attraction is favoured.

Question 178

consensus sequence for introns. They start with … and end with ..

Answer 178

GU and AG

Question 179

In a karyotype, what stage of mitosis are the cells usually viewed in?

Answer 179

metaphase - 2n 4C

Question 180

DNA polymerase has .. activity which allows it to remove the RNA primers.

Answer 180

5-3’ exonuclease activity

Question 181

what is a nucleosome? and what are the components

Answer 181

most fundamental unit of DNA packaging. consists of a central core of 8 histone proteins

Question 182

what bond do lipase cleave?

Answer 182

ester bonds between fatty acids and glycerol

Question 183

do exergonic reactions favour the reactants or products at equilibrium ? is the Keqilibrium less than or greater than 1

Answer 183

products. Greater

Question 184

what is the distinct property that cysteine has?

Answer 184

has the ability to form disulphide bonds with other cysteine residues

Question 185

what are the genetic predisposition to HNPCC

Answer 185

mutation to any one of the genes that codes for a protein involved in the mismatch repair pathway.

Question 186

when are double strand break repair pathways used? HR and NHEJ

Answer 186

double strand breaks and interstrand crosslink. Intrastrand uses numerous pathways but homologous recombination is one of them

Question 187

what is pharmacogenomics?

Answer 187

this is the study of the genetic composition of an individual to health identify there response for a given therapeutic

Question 188

why is the pKA of the histidine R group? why is this relevant to human biochemistry

Answer 188

6. This has the ability to be protonated and deprotonated under physiological conditions. often in the active site of enzymes as a proton donor and acceptor

Question 189

result of transcription is an .. molecule with sequence identical to the … DNA strand but with..

Answer 189

mRNA. coding/nontemplate/sense strand. U instead of T

Question 190

transcriptional activators can bind to … sequences (distal to the promoter) and interact with DNA of the promoter through DNA looping.

Answer 190

enhancer, DNA looping

Question 191

what is the molecular force that holds two strands of complementary DNA together?

Answer 191

hydrogen bond

Question 192

this inherited disorder is characterized by sun sensitivity. individuals may get freckling and subsequent neoplastic changes. patients have a defect in nucleotide excision repair.

Answer 192

xeroderma pigmentosum

Question 193

anabolism is typically … and … in nature?

Answer 193

endergonic and reductive.

Question 194

describe what a ganglioside is ?

Answer 194

glycosphingolipid (GSL) - 3 or more sugars , one of which is NANA ( N acetylneuraminic acid)

Question 195

DNA sequence that contains the coding information for that protein?

Answer 195

exon

Question 196

neurodegenerative disease that are characterized by amyloidosis

Answer 196

huntingtons, Parkinson’s, and Alzheimers

Question 197

what enzyme allows replication of the ends of chromosomes

Answer 197

telomerase

Question 198

regulation of the activity of the … enzyme in a metabolic pathway controls the metabolic flux through the pathway

Answer 198

rate limiting enzyme. irreversible committed step

Question 199

forces involved in tertiary structure of proteins?

Answer 199

van der waal forces, ionic, disulphide bonds, hydrogen bonds

Question 200

lysine is know to undergo which modifications?

Answer 200

hydroxylation, acetylation (histones), and methylation, ubiquitnylation

Question 201

3 forces that drive protein folding ?

Answer 201

hydrogen bonds, van der waal forces, and ionic bonds

Question 202

fatty acid aggregation with one layer is called a ??

Answer 202

micelle

Question 203

name 2 common chaperon proteins and 2 other proteins that aid in protein foldin?

Answer 203

HSPs and chaperoning. peptidyl propel cis trans isomerase and disulphide isomerase

Question 204

how does a lack of vitamin C (ascorbate) contribute to impaired collagen formation. what is this condition known as

Answer 204

can’t form hydroxyproline. scurvy

Question 205

what are CDRs of immunoglobulins. what is there role?

Answer 205

complementary determining regions. gives specificity for what antigen the AB will bind to

Question 206

DNA with 42% GC Composition - what are the individual base composition?

Answer 206

21% for G and also C.
29% for A and T individually

Question 207

origins of replication are typically … rich? why?

Answer 207

AT rich. these have only 2 hydrogen bonds while GC base pairs have 3 hydrogen bonds

Question 208

What is the exome?

Answer 208

part of the genome composed of exons. These are sequences that remain with the mature mRNA and can be translated in a polypeptide chain

Question 209

5’ cap functions to ? 1) protect from… 2) facilitates .. from the nucleus to the cytoplasm 3) .. for translation

Answer 209

5’ exonuclease, transport, start signal

Question 210

replication occurs in a … manner from the origin of replication?

Answer 210

bidirectional

Question 211

differences between RNA and DNA

Answer 211

RNA contains uracil instead of thymine. this base pairs also with adenine. RNA is typically single stranded (see exceptions with structure such as tRNA and primary miRNA)

Question 212

during transcription, the DNA is read … and the mRNA is transcribed…?

Answer 212

3 -5’. 5-3’

Question 213

epigenetic modifications of histones include. (4 of them)

Answer 213

acetylation, methylation and phosphorylation and ubiquitination

Question 214

these two disease are often a result of splice site mutations?

Answer 214

neurofibromatosis 1 and Menkes disease (increased copper in the body)

Question 215

chaotropic agents such as urea and guanidium hydrochloride disrupt which force that stabilizes protein structure?

Answer 215

hydrogen bonds

Question 216

what protein domain binds to phosphotyrosines?

Answer 216

SH2

Question 217

what is the fatty acid C16:0

Answer 217

palmitic acid

Question 218

this is a disorder caused by defects in nucleotide excision repair. patients have brittle hair, short stature, immature sexual development and skin abnormalities.

Answer 218

trichothiodystrophy

Question 219

protein sequencing done by cleaving amino acids one by one from the end and sequencing each amino acid ?

Answer 219

Sanger sequencing

Question 220

nucleosomes fold up to produce a ??

Answer 220

30 nm fiber

Question 221

this enzyme separates the two strands of DNA during transcription ?

Answer 221

helices

Question 222

Because DNA replication uses both strands of the parent DNA to ultimately 2 identical copies of DNA, it is termed ?

Answer 222

semi conservative

Question 223

many collagen triple helices assemble into a collagen…?

Answer 223

fibril

Question 224

humans chromosomes are usually studied in what type of cells ?

Answer 224

Dividing cells - e.g cultured T lymphocytes, skin fibroblast, fetal cells of amniotic fluid or chorionic villi

Question 225

trans fatty acids can lead to an increase in … cholesterol

Answer 225

LDL

Question 226

signals for cells to activate catabolic pathways

Answer 226

low NADH, low NADPH, low ATP to ADP ratio

Question 227

what is the role of the centromere?

Answer 227

attachment site of sister chromatids. During mitosis, the mitotic spindle attaches here and allows each chromatid to be pulled towards opposing poles

Question 228

describe why the wobble hypothesis exists?

Answer 228

61 codons exist that code for a specific amino acid. There is not 61 different tRNA. The 3rd bae is less discriminatory than the other 2 bases therefore all codons can be accommodated with a tRNA

Question 229

if something is reduced, it is the … agent

Answer 229

oxidizing agent

Question 230

Bcr-abl is a … gene?

Answer 230

fusion

Question 231

main roles of lipids?

Answer 231

structural aspect of the cell membrane, energy reserves (TGs), vitamins and hormones, bile acids for lipid solubilization, biological signalling molecules (DAG)

Question 232

what are the main roles of post translational modification?

Answer 232

can direct protein to a specific location (RAS protein gets a lipid tail added on for localization to the plasma membrane), influence protein activity, influence interaction with other proteins, control protein stability

Question 233

human metabolic storage disorders characterize]d by the accumulation of harmful quantities of glycosphingolipids and phosphosphingolipids. what organelle and associated enzymes is not working in patients with one of these disorders

Answer 233

sphinolipidoses. lysosomal storage disease - eg tay Sachs disease

Question 234

true or false. tertiary protein structure is determined by the primary sequence but may require additional chaperone proteins and accessory enzymes

Answer 234

true

Question 235

what does hydroxyproline in collagen chain contribute to the formation of triple helical collagen ?

Answer 235

offers more hydrogen bonds

Question 236

during DNA replication the enzyme… adds a new nucleotide to the free … of the DNA strand

Answer 236

DNA polymerase. 3’ OH

Question 237

name of the bond formed between sugar and base of a nucleotide ?

Answer 237

N-glycosidic bond

Question 238

what is the main take home message from the ribonuclease experiment in regard to protein folding?

Answer 238

protein denatured by addition of 2-mercaptoethanol (reduces disulphide bonds) and urea. when these agents were removed, the protein spontaneously refolded to native conformation. sequence alone determines the shape of a protein

Question 239

true or false. MMR pathway uses non-template strand for reference to correct mismatch?

Answer 239

false. non-template is the newly synthesized strand. It will

Question 240

if the PH is less than the PKA, what does that mean for the protonation state of that group?

Answer 240

it is protonated. if PH is greater than PKA then that group is deprotonated

Question 241

aspirin is an inhibitor of … enzyme

Answer 241

cyclooxyrgenase enzyme

Question 242

immunoglobulins consist of 2 … and 2..?

Answer 242

light chains
heavy chains

Question 243

why is formation of triacylglycerols an efficient way to store energy? more so than glycogen

Answer 243

because fatty acids have been esterified to glycerol they are no longer hydrophilic. no salvation shell is required. glycogen needs a salvation shell (polar)

Question 244

describe how DNA has polarity?

Answer 244

the ends of DNA are not identical - 3’ OH and 5’ phosphate of each end are not symmetrical to the other end of the DNA strand

Question 245

what is the beta turn stabilized by?

Answer 245

hydrogen from carbonyl to amide three residues down

Question 246

GPLs are a major component of the …?

Answer 246

cell membrane

Question 247

what do chromosomes include?

Answer 247

DNA and associated proteins

Question 248

what are the components of ceramide?

Answer 248

sphingosine + fatty acid attached to the amino group of C2 of sphingosine (amide bond)

Question 249

pH extremes disrupt which stabilizing force of protein structure?

Answer 249

ionic bonds

Question 250

many collagen fibrils come together to form a collagen…?

Answer 250

fiber

Question 251

name the 5 most common GPLs

Answer 251

phosphatidyl serine, inositol, choline, ethanolamine, glycerol

Question 252

active/ open chromatin that can be transcribed easily

Answer 252

euchromatin

Question 253

what principal describes the fact that equilibrium can change if products or reactants are altered

Answer 253

le chataliers principle

Question 254

region of tRNA that can complementary base pair (with exception) to the codon of the mRNA

Answer 254

anticodon

Question 255

what is required for the formation of hydroxyproline?

Answer 255

prolly hydroxylase, alpha-ketoglutarate, and ascorbate (vitamin C)

Question 256

True or false. Approximately 1% of the human genome is protein encoding

Answer 256

True

Question 257

what cell type has no nuclear DNA?

Answer 257

Red blood cell

Question 258

what are the two roles of DNA?

Answer 258

Transmit and store information – transmit to identical daughter cells in the case of mitosis or to haploid gametes in meiosis

Question 259

what is HNPCC?

Answer 259

hereditary non polyposis colon cancer. inherited tendency to develop colon and other associated cancers (80% chance)

Question 260

H1 histone interacts with DNA located in the … region. DNA between the DNA that interacts with the core histone proteins.

Answer 260

linker region

Question 261

some proteins once translated have there N terminal methionine and maybe some additional amino acids cleaved off. This is achieved via the action of ?

Answer 261

N terminal methionine aminopeptidases

Question 262

2 groups of nitrogenous bases and what is there difference ?

Answer 262

Purines (A,G) - double ringed structure and pyrimidines (C,T) - single ringed structure

Question 263

what are the 5 main classes of lipids ?

Answer 263

fatty acids
triglycerides
glycerol phospholipids
sphingolipids
cholesterol

Question 264

proteins fold into a conformation of … ? this is determined from the … sequence

Answer 264

lowest energy. primary

Question 265

dwarfism, sensitivity to sunlight, premature aging, deafness and mental retardation or symtoms of what disorder?

Answer 265

cockayne syndrome

Question 266

in sickle cell anemia a point mutation causes a glutamic acid to become a …? what is the effect of this mutation

Answer 266

valine. this causes beta chains to stick together. repellent force of glutamic acid with other glutamic acids is gone.

Question 267

which two histone core proteins are ubiquitinated ?

Answer 267

H2A and H2B

Question 268

beta turns are accomplished over … residues ?

Answer 268

4

Question 269

globoside is ceramide + ….

Answer 269

2 or more sugars, not including NANA

Question 270

what has been the 3 results of genetic advances in healthcare?

Answer 270

Cancer diagnosis and treatment, Non invasive prenatal screening, personalized medicine which includes pharmacogenomics

Question 271

this protein is found in muscle cells and binds oxygen. it has 1 subunit unlike another protein that binds oxygen .

Answer 271

myoglobin

Question 272

… tails of core histones protrude from the nucleosome ? what specific amino acid is modified here ?

Answer 272

N terminal. Lysine. This effects how the chromatin is packed

Question 273

partial proteolysis is an example of a protein modification. what protein undergoes this?

Answer 273

Insulin. C chain is cleaved out
A and B chains now only connected via disulphide bonds

Question 274

name 4 pathways that can be utilized to repair DNA

Answer 274

mismatch repair pathway, base excision repair, nucleotide excision repair, double stranded break repair (non homologous end joining or homologous recombination)

Question 275

in humans … energy released by chemical reactions is transducer into … energy and this is used to drive the energy requiring process of the cell

Answer 275

free energy
chemical energy

Question 276

allosteric regulation refers to…

Answer 276

binding of an effector molecule to an enzyme not at the active site

Question 277

what force/s are secondary protein structures stabilized by? what atoms are involved

Answer 277

hydrogen bonds only. only main chain atoms are involved. R groups are not involved

Question 278

triglycerides are … % of dietary lipid consumption

Answer 278

90%

Question 279

… are amphipathic lipids which act as biological detergents and emulsify lipids

Question 280

what are the names of the 3 lipases that the bodies utilizes in digestion of triglycerides?

Question 281

lipase cleave …. bonds between glycerol and fatty acids

Answer 281

ester

Question 282

bile acids are synthesized in the …. and stored in the …?

Question 283

bile salts are more … and less … compared to bile acids

Question 284

the vast majority of bile salts are not excreted but rather … in the … of the GI tract

Answer 284

rebaorbed

ileum

Question 285

bile salts are derived from which class of lipids

Question 286

process by which large lipids droplets disperse into smaller ones. This increases the surface area

Question 287

this protein anchors pancreatic lipase to the water-lipid interface and prevents lipase from being washed away by bile salts

Question 288

Orlistat /xenical is an inhibitor of what enzyme

Question 289

side effects of increased lipid retention in the gut

Question 290

break down of lipids in the small intestine leads to the formation of mixed ….?

Question 291

contents of mixed micelles ?

Question 292

during lipid absorption. … and … can enter enterocytes via passive diffusion. … and … can enter enterocytes via facilitated diffusion

Question 293

free fatty acids, cholesterol, DAG, MAG are utilized within the enterocytes to resynthsize what?? This occurs where within the cell

Answer 293

triacylglycerols, cholesterol esters, phospholipids

smooth endoplasmic reticuluum

Question 294

… consist of lipids packaged with apolipoproteins, derived from enterocytes

Question 295

true or false. chylomicrons first enter blood circulation?

Question 296

free glycerol absorbed in enterocytes and not reconstituted with fatty acids to make TAGs can directly enter?

Answer 296

blood circulation

Question 297

plant sterols can be used to block … absorpotion? they compete with … for incorporation into mixed…? plant sterols are however not… into enterocytes

Answer 297

cholesterol

cholesterol

micelles

Question 298

TAG are too … to be digested and absorbed. they must be … by bile salts and broke down to … , …. and …

Answer 298

hydrophobic

solubilized

MAGs, DAGs and freet fatty acids

Question 299

the core of lipoproteins consists primarily of … and …. . why are they found here

Answer 299

triglycerides

Question 300

‘skin’ of lipoproteins primarily constains … , … , and …. 2 of these are lipid deriviatievs, why can they be found here ?

Answer 300

phospholipids

cholesterol esters

apolipoproteins

Question 301

LDL are not made in the liver but evolve from ….

Answer 301

VLDL

Question 302

order the lipoproteins from largest to smallest. from going from largest to smallest there is an increase in ….?

Answer 302

chylomicrons, VLDL, IDL, LDL, HDL

Question 303

these two lipoproteins are the main carriers of triglycerides ?

Answer 303

chylomicrons and VLDL

Question 304

ApoB-100 has what function?

Answer 304

binds to LDL receptor on cells and allows uptake of lipoprotein

Question 305

what is the main function of ApoC-2

Answer 305

binds to and activates lipoprotein lipase, which is required for the breakdown of TAGs

Question 306

nascent chylomicrons contain Apo.. but acquire additional Apos… from HDL

Answer 306

B48

A,C,E

Question 307

major function of chylomicron is to transport dietary … from the intestine to tissues. what tissues specifically?

Answer 307

TAGs

skeletal and cardiac muscle, lactating mammary glands, liver and adipose tissue

Question 308

… breaks down TAGs contained in lipoproteins so they can be taken up by cells

Answer 308

LPLs

Question 309

LPLs are found on the … surface of … cells. They are linked to these cells via …

Answer 309

luminal

endothelial cells

proteoglycans

Question 310

Insulin activates lipoprotein lipase isoforms on endothelial cells of … tissue.

Answer 310

adipose tissue

Question 311

… activates lipoprotein lipase isoforms located on the endothelial surface of … tissue

Answer 311

muscle (skeletal and cardiac)

Question 312

TAG hydrolysis of chylomicrons reduces … and increases … of lipoprotein. now we have a …

Answer 312

size

density

chylomicron remnant

Question 313

chylomicrons remnants are taken up by the liver via …. . this requires Apo… which binds to which receptor on hepatocytes ?

Answer 313

receptor mediated endocytosis

ApoE

LDLR family

Question 314

… transports endogenous products, whereas..transport exogenous (dietary) products.

Answer 314

VLDL

chylomicrons

Question 315

VLDL mainly transport … from liver to adipose tissue for … or peripheral tissue (cardiac and skeletal muscle) for …

Answer 315

TAGs

storage

utilization

Question 316

VLDL TAGs hydrolyzed by … forming VLDL … (also called …)

Answer 316

LPLs

remnants

IDL

Question 317

50% of VLDL remnants (IDL) recycle in the … (requires Apo..). Remainder converted to …

Answer 317

liver

apoE

LDL

Question 318

LDL formed from … after … content of IDL enriched (and … content depleted). this occurs via exchange with …

Answer 318

IDL

cholsterol/cholsterol ester

triglyceride

HDL

Question 319

Apo… is critical to function of LDL

Answer 319

B-100

Question 320

LDL is a major … carrier to peripheral tissue

Answer 320

cholesterol

Question 321

which peripheral tissues require cholsterol?

Answer 321

adrenal gland for the production of steroid hormones - cortisol, aldosteron

gonads - testosterone and estradiol ( steroid hormones)

Question 322

what are the major function of HDLs?

Answer 322

transport cholesterol from tissues to the liver

source of numerous apoliproteins

also associarted with other proteins (LCAT, PTLP)

Question 323

… is an autosomal dominant disorder that leads to grossly elevated LDL. … receptor absent or impaired or can also be caused by Apo… deficits.

Answer 323

familial hypercholesterolemia

LDL

ApoB-100

Question 324

these are cholesterol deposits in the skin or joints. what inherited disorder is know to cause these?

Answer 324

cutaneous or articual xanthomas

familial hypercholesterolemia

Question 325

… are used to lower levels of LDL cholsterol. They work by inhibiting endogenous sysnthesis of cholesterol in the liver

Answer 325

statins

Question 326

what are 4 intervents to treat elevated LDL cholesterol. what is their mode of action

Answer 326

statins

bile acid sequestrants - prevent reabsorption of bile acids in the ileum

LDL apheresis -

Question 327

excess plasma LDL can accumulate in the … of blood vessels. LDL can then be oxidized which is a pro… signal.

Answer 327

intima

inflammatory

Question 328

macrophages take up oxLDL by a … mechanism. This leads to macrophages to become … cells and generate … streak

Answer 328

scavenger receptor

foam

fatty

Question 329

TAGs are a more efficeient way to store as they do not require a … shell.

a gram of triglycerides has … times more energy than 1 g of glycogen

Answer 329

solvation

2

Question 330

what pathways does the cell need products from the synthesize fatty acids?

Answer 330

NADPH from PPP

NADPH from the citrate shuttle

acetyl coa- from the citrate shuttle also

Question 331

reference to citrate shuttle. pyruvate in the mitochondria can be used to make … and …. these two products combine to form…. this is then secreted into the cytosol. … is broken down to … and ……

… is a building block of fatty acid synthesis and the other is mdae into malate. male is then oxidized to produce pyruvate and …

Answer 331

acetyl coa and oxaloacetate

citrate

acetyl coa and oxaloacetate

acetyl coa

NADPH

Question 332

Fatty acid synthesis is utilized for .. storage in time of

Answer 332

energy

excess

Question 333

… and .. are major sites of fatty acid synthesis

… tissue is main site of energy storage

Answer 333

liver and mammary gland

adipose

Question 334

in fatty acid synthesis acetyl coa (2C) is converted to … (3C)

Answer 334

malonyl

Question 335

fatty acid chains are elongated by the sequential addition of … carbon units from … in a series of 4 reactions (what are these 4 reactions??)

Answer 335

2

malnoyl coa

condensation, reduction, dehydration, reduction

Question 336

elongation of fatty acid chains continues until the Fatty acid chain is … carbons in length. further elongation and desaturation requires an alternative set of …

Answer 336

16 (palmitic acid)

enzymes

Question 337

humans cannot introduce double bonds after Carbon …. this is why we need to consume essential fatty acids (what are the two metioned essential fatty acids ?)

Answer 337

9

linoleic and linolenic acid

Question 338

acetyl coA cannot be directly transported into the cytosol from the mitochondria. what is the solution ?

Answer 338

citrate shuttle

Question 339

most acetyl coa is generated in the mitochondria via … enzyme (prelude to TCA cycle) and … of fatty acids

Answer 339

pyruvate dehydrogenase

beta oxidation

Question 340

the citrate shuttle generates 1 … but costs 1 …

Answer 340

NADPH

ATP

Question 341

citrate is the first intermediate in the …

if there is high levels of citrate in the cell what does this signify?

Answer 341

TCA cycle

increased energy in the cell and high flux through the TCA cycle

Question 342

this enzyme is responsible for the formation of malonyl coa from acetyl coA.

what cofactor does this enzyme require

Answer 342

acetyl coa carboxylase (ACC)

biotin

Question 343

formation of malonyl coa during fatty acid synthesis represents the … … step in fatty acid synthesis. This is because this reaction is highly … because it is coupled to … hydrolysis

Answer 343

rate limiting

exergonic

ATP

Question 344

Acyl carrier protein is attached to reaction intermediates of fatty acid synthesis via the … group of phosphopantetheine

Answer 344

thiol (-SH)

Question 345

in terms of function ACP is like a large ….

Question 346

fatty acid synthase is a … complex

Answer 346

multienzyme

Question 347

FAS has … distinct enzyme activities

Answer 347

5

Question 348

the first step of fatty acid synthesis involves the transfer of the acetyl group of acetyl coa to …. which is catalyzed by …

also malnoyl coa is attached to ACP by

Answer 348

Beta-ketoacyl-ACP synthase (KS)

MAT

MAT

Question 349

the first reaction of fatty acid synthesis involves the condensation of 2C … unit and 3C … unit with loss of …

this reaction is catalyzed by

Answer 349

acetyl

malonyl

b-ketoacyl-ACP synthase

Question 350

elongation of fatty acid chain after generation of 4 carbon butyrl ACP.

Butryl is transfered to … and …. is transferred onto ACP

this is achieved by the enzyme …

Answer 350

b-ketoacyl-ACP- synthase (KS)

malonyl unit of malnoyl coa

MAT

Question 351

palmitate the major end product of fatty acid synthesis is cleaved from ACP by …

Answer 351

thioesterase

Question 352

fill in the coefficnets for the synthesis of palmitate

Acetyl coA + malonyl coA + NADPH + H+ —– palmitate + CO2 + NADP+ + coA + H20

Answer 352

1, 7, 14, 20, 1, 7,14, 8,6

Question 353

synthesis of malonyl coa (7 of them)

write out the reaction

Answer 353

7 acetyl coa + 7CO2 + 7ATP —– 7 malonyl coA + 7ADP + 7Pi + 14H+

Question 354

of the 14 NADPH required for the synthesis of palmitate, 8 are from the …. and 6 are from ….

how many ATP are required in total to synthesis citrate

Answer 354

citrate shuttle (costs 1 ATP per NADPH)

Pentose Phsophate pathway (costs 3 ATP)

18 (7 to make malonyl coA)

Question 355

elongation of palmitate does not occur in the cytosol unlike sysnthesis of palmitate itself. where else does it occur ?

Answer 355

endoplasmic reticuulum and mitochondria

Question 356

where does fatty acid desaturation take place? what are the enzymes referred to as ?

Answer 356

endoplasmic reticuluum

desaturases

Question 357

what is the key control point in fatty acid synthesis ?

Answer 357

transformation of acetyl coa to malonyl coa via action of ACC (acetyla coA carboxylase)

Question 358

how does malonyl coA inhibit beta-oxidation ?

Answer 358

inhibits the enzyme carnitine transferase. carnitine added to fatty acids allows them to move into the mitochondria where beta oxidation occurs

• this is inhibited when there is high levels of malonyl coA

Question 359

acetyl coa carboxylase (ACC) is subject to …. regulation and reversible … modification

Answer 359

allosteric

covalent (phosphorylation)

Question 360

monomeric ACC is … while polyermic filamentous ACC is …

Answer 360

inactive

active

Question 361

palmitoyl-coA is a … allosteric regulator of…

Answer 361

negative

Acetyl coa carboxylase

Question 362

…. is a positive allosteric regulator of ACC activity. it signals energy abundance within the cell

Answer 362

citrate

Question 363

regulatory effects of … and … on ACC activity or dependent on the …. state of the enzyme

Answer 363

palmitoyl - coA

citrate

phosphorylation

Question 364

phosphorylation of ACC by …. causes the enzyme to be…

which hormone activates the enzyme that phosphorylates ACC

Answer 364

AMP - activated protein kinase

inactive

glucagon

Question 365

…. under the control of which hormone … dephosphorylates ACC and leads it to be active

Answer 365

protein phosphatase 2 A

insulin - signals energy abundance

Question 366

PPARS (peroxisome proliferator activated reecptors) play essential roles in ….

Answer 366

cell differentiation, inflammation and metabolism

Question 367

endogenous PPAR ligands are mostly …

Answer 367

polyunsaturated fatty acids

eicosanoids

Question 368

PPARS once bound by ligand form heterodimers with … and bind promoter elements of target genes

Answer 368

LXR receptor

Question 369

once are the main consequences of PPAR activation ? what effect does this have for diabetes (type 2)

Answer 369

increase insulin sensitivity, lower fatty acid, triglyceride and cholesterol levels

tries to switch energy utiization from primarily lipid based to carbohydrate

Question 370

what are thiazolidines? in which disease is this drug most commonly used in

Answer 370

PPAR gamma agonist

type 2 diabetes

Question 371

what are the beneficial insulin sensitizing actions of thiazolidines?

Answer 371

increase glut 4 expression

dcrease TNF alpha, resistin, and IL-6

-last 3 decrease increase insulin resistance typically

Question 372

what is the overall beneficial metabolic action of thiazolidines?

Answer 372

net transfer of TAGs to adipose tissue

Question 373

what effects does PPAR gamma agonist have on the liver?

Answer 373

decrease gluconeogensis

decrease beta oxidation

increase glucose utilization

Question 374

PPAR gamma agonist have what effect on muscle tissue?

Answer 374

decrease transport of fatty acid transport into them

decrease fatty acid oxidation

increase glucose utilization

Question 375

C75 has dual function. it is an inhibitor of … and an acvtivator of…

Answer 375

Fatty acid synthase (FAS)

carnitine palmitoyltransferase

Question 376

tricostan is a … which inhibits … one of the enzymes of the Fatty acid synthase multienzyme complex

Answer 376

broad spectrum antibiotic

enoyl ACP reductase (ER)

Question 377

C75 has shown to not only decrease fatty acid synthesis but also elicits effects in the … where it promotes anorexigenic pathways and decreases orexigenic pathways

Answer 377

hypothalamus

Question 378

inhibitors of Acetyl coa carboxylase are used as a therapeutic to treat…

in adipose tissue these inhibitors have what effect

in muscle cells these inhibitors have what effect

Answer 378

obesity

inhibit fatty acid synthesis

decrease malonyl coa and there promote beta oxidation

also have insulin sensitive effects

Question 379

main sites of triglyceride synthesis

where in the cell does this occur

Answer 379

intestine, adipose and liver

mitochondria, ER and peroxisome

Question 380

in triacylglycerol synthesis where is glycerol-3-phosphate derived from?

Answer 380

G-3-P is an intermediate of glycolysis

in the liver glycerol can be phosphorylated by glycerol kinase

Question 381

what are the 4 steps of Triacylglycerol synthesis?

Answer 381

1) generation of G-3P
2) sequential addition of 2 fatty acid chain
3) dephosphorylation
4) addition of third fatty acid chain

Question 382

what is the purpose of triglyceride synthesis in the liver? what is the purpose of TAG synthesis in adipose ?

Answer 382

for distribution purposes

for storage

Question 383

true or false? muscle cells can do fatty acid synthase because they express the enzyme fatty acid synthase

Answer 383

false - do not express enzyme

Question 384

Lipases cleave … bonds of …. ??

Answer 384

ester

triglycerides

Question 385

60-80% of energy needs of mammalian … and …. muscle … …. are met by beta oxidation

Answer 385

cardiac muscle

skeletal muscle

liver

kidneys

Question 386

Liver is an important site of fatty acid metabolism. this includes … … and … synthesis for distribution to other tissues (incorporated into VLDL) ?

Answer 386

oxidation of FAs for energy

synthesis of FAs for energy storage

Triglycerides

Question 387

Insulin …. lipolysis in the adipose tissue

Answer 387

inhibits

Question 388

glucagon … lipolysis in the adipose tissue which generates … and … which can be taken up by the …

Answer 388

stimulates

non-esterified free fatty acids

triglycerides

liver

Question 389

…. and … stimulate lipolysis in the adipose tissue.

Answer 389

glucagon

norepinephrine

Question 390

… is released in response to low glucose in the plasma. This will stimulate lipolysis in the adipose tissue. fatty acid will be used in the liver to generate ATP which can fuel …. to increase blood glucose levels

Answer 390

glucagon

gluconeogenesis

Question 391

glucagon and norepinephrine active this enzyme in adipose tissue which acts to release free fatty acids and glycerol from triglyceride stores.

Answer 391

hormone sensitive lipase

Question 392

… inhibits the action of hormone sensitive lipase within adipocytes.

Answer 392

insulin

Question 393

glucagon and norepinephrine bind to this transmembrane receptor on target cells ? this leads to the activation of … which enzyme that catalyzes the cyclicization of … to … which goes on to activate which kinase??

Answer 393

G-coupled protein receptor (GPCR)

adenyl cyclase

ATP

cAMP

protein kinase A.

Question 394

protein kinase A (PKA) phosphorylates … in adipose cells thereby activating it leading to the breakdown of triglycerides .

Answer 394

hormone sensitive lipase

Question 395

Protein kinase A phosphorylates hormone sensitive lipase and … in adipocytes.

… is a lipid droplet protein and phgosphprylation of it is essential for mobilization of triacylglcerol

Answer 395

peripilin

Question 396

Free fatty acids once released from adipocytes bind … in blood plasma which allows them to be soluble in circulation.

Answer 396

serum albumin

Question 397

glycerol that has been released from adipocytes can be taken up by hepatocytes.

within hepatocytes glycerol can be used for … through conversion to pyrvate and/or … through conversion to glucose

Answer 397

glycolsysis

gluconeogenesis

Question 398

glycerol and/or fatty acids can also be used for complex lipid synthesis including … and …

Answer 398

glycerophospholipids

sphingolipds

Question 399

beta oxidation occurs in the … of the cell

Answer 399

mitochondrial matrix

Question 400

during beta oxidation fatty acids are activated by linkage to …

Answer 400

Coenzyme A

Question 401

each cycle of beta oxidation removes … carbons and generates 1 … and 1 …

Answer 401

2 carbons

NADH

FADH2

Question 402

synthesis of Fatty acids occurs in the … while oxidation of fatty acids occurs in the … this serves to … the 2 pathways

Answer 402

cytosol

mitochondria

compartmentalize

Question 403

Inorder to activate fatty acids for beta oxidation they must be joined to …. which is catalyzed by … and requires 1 … to drive this naturally endergonic rxn

Answer 403

CoA

acyl-CoA synthestase

ATP

Question 404

acyl-CoA synthetase is located …

Answer 404

on the outer mitochondrial membrane facing the cytosol

Question 405

during beta oxidation how are short chain acyl-coa molecules transported into the mitochondrial matrix? what constitues a short chain fatty acyl chain

Answer 405

they can freely diffuse across the 2 membranes of the mitochondria

less than 12 carbons

Question 406

fatty acl coa molecules greater than 12 carbons transport into the mitochondrial matrix for beta oxidation.

step 1- remove .. and attach … to fatty acid

step 2 - transporter can move … into the mitochondrial matrix

step 3 - when in the mitochondrial matrix … is removed and … is added to the fatty acid

Answer 406

CoA

carnitine

acyl carnitine

carnitine

CoA

Question 407

4 rxns involved in each cycle of beta oxidation ?

Answer 407

oxidation,

hydration,

oxidation,

cleavage

Question 408

each cycle of beta oxidation generates 1 … and 1 … both of which are high energy electron carriers

Answer 408

NADH

FADH2

Question 409

… deficiency or deficiency its associated enzyme …. can impair movement of acyl coa (longer than 12 carbons) into the mitochondrial matrix

Answer 409

carnitine

carnitine acyl transferase

Question 410

what are the causes of carnitine deficiency (3 of them) This molecule is attached to fatty acids greater than … carbons to allow transport into the mitcochondrial matrix

Answer 410

dietary deficiency

impaired liver synthesis

impaired renal reabsorption

Question 411

what are the clinical metabolic manifestations of carnitine or carnitine acyl transferase deficiency (2) ?

Answer 411

hypoketotic - ketone bodies derived from acetyl coa which is the product of beta oxidation.

hypoglycemia - need ATP from beta oxidation to fuel gluconeogenesis. also cells like muscle, kidney and liver cannot use fatty acids for energy so they must consume glucose from circulation

Question 412

what ar the multisystem complications of carnitine or carnitine acyl transferase deficiency ?

Answer 412

affects CNS, liver, skeleta and cardiac muscle

organomegaly - increased fat deposition

myopathies

Question 413

treatments for carnitine defiency or carnitine acyl transferase deficiency?

what should patients avoid (2)?

Answer 413

oral carnitine

dietary supplementation with short chain fatty acids - these do not need to have carnitine attached to move into the matrix of the mitochondria

high carbohydrate and low fat diet - carbohydrates are the main source of energy

avoid fasting

strenous exercise

Question 414

reaction 1 of the beta oxidation is a … reaction ?

this is catalyzed by which enzyme

Answer 414

oxidation

acyl-CoA dehydrogenase

Question 415

there are … isoforms of acyl-CoA dehydrogenase and each acts on different …. length fatty acl-CoA

Answer 415

3 - long, medium and short

lengths

Question 416

reaction product of acyl CoA dehydrogenase generates a double bond in the … configuration

Answer 416

trans

Question 417

what disorder is reffered to in short as MCAD?

what is the inheritance pattern

Answer 417

medium chain acyl CoA dehyrodgenase deficiency

autosomal recessive

Question 418

what is the biochemical profile of medium chain acyl-CoA dehydrogenase deficiency? (3)

Answer 418

intermittent hyoglycemia

intolerance to prolonged fasting - fatqiue/lethargy

medium chain dicrboxylic aciduria - by product of an alternative oxidative pathway of medium chain fatty acids

Question 419

is there alternative pathway for oxidation of medium chain fatty acids to beta oxidation ? if so what can the byproduct of this pathway lead to

Answer 419

yes

medium chain dicarboxylic aciduria

Question 420

why are the physiological effects of MCAD severe?

Answer 420

medium chain fatty acids are the bulk of what we consume

Question 421

how many cycles of beta oxidation are involved in the complete oxidation of palmitic acid ? what are the products of the complete oxidation?

does complete oxidation of palmitic acid require energy require energy input if so how much?

Answer 421

7 cycles

8 acetyl coa

7 NADH

7 FADH2

yes, activation of palmitic acid to palmitoyl CoA

Question 422

FADH2 and NADH generated from fatty acid oxidation can…

Answer 422

donate electrons to the electron transport chain and therefore be used to generate ATP by oxidative phosphorylation

Question 423

complete oxidation of palmitic acid can ultimtaley generate how many ATP? whereas 1 molecule of glucose can generate … ATP

Answer 423

108

32

Question 424

Beta oxidation of uneven numbered carbon fatty acids.

undergo beta oxidation until … carbons remain, this fatty acyl linked to CoA is called ???

…. is then carboxylated to become a 4 carbon fatty acyl CoA molecule called? this molecule is an intermediate of the … cycle

Answer 424

3

propionlyl CoA

Propionyl CoA

Succinyl CoA

TCA

Question 425

Oxidation of MUFAs and PUFAs requires additionals… that are not required for oxidation of saturated fatty acid

… double bonds are a substrate for beta oxidation not … double bonds

this enzyme converts cis double bonds of MUFAs and PUFAs to trans configuration

this enzyme reduces a trans + cis configuration to just a single trans isomer

after the action of these enzymes occur beta oxidation can resume as normal

Answer 425

enzymes

trans, Cis

enoyl CoA isomerase

2,4- dienoyl CoA reductase

Question 426

where does the inital oxidation of very long or branched Fatty acids occur

Answer 426

peroxisome

Question 427

oxidation of very long or branched fatty acids generates … and … which are high energy electron carriers, however these are …. in the peroxisome using molecule oygen forming h202 which is inactivated by catalse

Answer 427

NADH

FADH2

reoxidized

Question 428

peroxisomal oxidation of branched or very long fatty acids occurs until the linear chain is … carbons long. After this the acyl-Coa molecule is transferred to the … very it is further oxidized to completion

Answer 428

18

mitchondrial matrix

Question 429

disorder relating to impaired peroxisomal fatty acid oxidation can occur due to ? (3)

Answer 429

peroxisomal biosynthesis

deficiency of peroxisomal fatty acid oxidative enzymes

peroxisomal FA transport

Question 430

disorders of peroxisomal fatty acid oxidation lead to accumulation of … and … fatty acids ?

this can lead to CNS manifestation including … which is degeneration of the white matter of the brain

Answer 430

long chain

branched chain

leukodystrophy

Question 431

what are the 3 peroxisomal fatty acid oxidation disorders related to impairment of peroxisomal biosynthesis ?

what gene is commonly mutated in all 3 ?

Answer 431

Zellwegers syndrome

infantile refsum disorder

neonatal adrenoleukodystrophy

Peroxin (PEX)

Question 432

what is the one disorder of peroxisomal fatty oxidation that is due to a mutation in an fatty acid oxidative enzyme ?

what enzyme is mutated

Answer 432

adult refsum disease

phtenic acid oxidase

Question 433

what is the one disoder of peroxisomal fatty acid oxidation that is due to mutation in gene that codes for a fatty acid transporter that brings them into the peroxisome ?

what functional FA transport is absent ?

Answer 433

X linked adrenoleukodystrophy

ABCD1

Question 434

lorenzos oil was used to treat …

it can prevent … synthesis of long chain fatty acids

Answer 434

X linked adrenoleukodystrophy

endogenous

Question 435

Regulation of fatty acid oxidation occurs at the level of which enzyme ?

which product of fatty acid synthesis regulates this enzyme and how?

how do insulin an glucagon reguate the production of malonyl CoA

Answer 435

carnitine acyl transferase 1

malonyl CoA- commited step of fatty acid synthesis

inhibits the activity of carnityl acyl transferase

insulin leads to dephosphorylation of ACC which leads to increased productin of malonyl - insulin signals that we do not need to use fatty acids for oxidation

glucagon leads to phosphorylation of ACC and reduces its activity - less malonyl CoA then more beta oxidation

Question 436

some acetyl CoA produced by beta oxidation may be converted to … bodies.

Name 2 of these molecules

Answer 436

ketone

acetoacetate

beta hydroxy buytrate

Question 437

ketone bodies are made by the … and can be used as an alternative energy source by the …? In these tissues it can be converted to … and oxidized by the TCA cycle

Answer 437

liver

brain, heart and muscle

acetyl CoA

Question 438

In prolonged fasting … will be oxidized to … and some of the … will be converted to … and released into circulation which can be used as an energy substrate numerous other tissus

Answer 438

fatty acids

acetyl CoA

ketone bodies

Question 439

ketone bodies are a major source of energy for the … during starvation ?

Answer 439

brain

Question 440

one of the key characteristics of ketone bodies is that they are water … therefore do not require … in the blood during transport

Answer 440

soluble

serum binding protein

Question 441

ketone bodies are a salvage system to utilize excess … generated in the liver

Answer 441

acetyl CoA

Question 442

In type 1 diabetes … defiency causes liver to switch metabolism to … and .. ./… catabolism

Answer 442

gluconeogenesis

fat and protein

Question 443

prolonged gluconeogenesis in T1DM depletes … which is an intermediate of the TCA cycle and excess fatty acid oxidation leads to a surplus of …

Excess … is shunted towards …. formation

Answer 443

oxaloacetate

acetyl CoA

acetyl CoA

ketone body

Question 444

excessive concentratin of ketone bodies in the blood will … the pH and increase the … of blood. The consequences of this are (2)?

Answer 444

lower

increase

acidosis (ketoacidosis)

dehydration - movement of fluid from the interstitium to circulation

Question 445

cholesterol synthesis mainly occurs in the ?? (3)

Answer 445

liver

intestine

steroidogenic tissues (adrenal gland, gonads)

Question 446

Carbon atoms of cholesterol are derived from the … group of ….

… must be transported out of the mitochindrial matrix, which achieved by the … which is also used for fatty acid synthesis

Answer 446

acetyl

acetyl CoA

acetly CoA

citrate shuttle

Question 447

cholesterol synthesis starts in the … and is finished in the … of the cell

Answer 447

cytosol

endoplasmic reticuulum

Question 448

cholesterol synthesis requires … as a cofactor, which offers … power for the pathway

Answer 448

NADPH- involved in numerous biosynthetic pathways

reducing

Question 449

step 1 of cholesterol synthesis involves the conversion of … acetyl CoA molecules to form …

… is then reduced to from … and this reaction is catalyzed by …

Answer 449

3

HMG CoA

HMG CoA

mevalonate

HMG CoA reductase

Question 450

conversion of … to … by … is the rate limiting step in cholesterol synthesis

Answer 450

HGM CoA

mevalonate

HMG CoA reductase

Question 451

3 mechanisms to regulate HMG CoA reductase

1. Phosphoryaltion by …. which … the enzyme
2. enzyme … is regulated by cholesterol levels. High cholsterol than decreased….
3. increased cholesterol can also regulate the levels of HMG CoA reductase at the level of …. mediated by

Answer 451

AMP-activated protein kinase

half life

transcription

sterol regulatory element binding protein (SREBP)

Question 452

how does cholesterol regulate the transcription of HMG CoA reductase gene?

Answer 452

cholsterol will complex with sterol regulatory element binding protein (SREBP) and translocate to the nucleus and act as a transcription factor - decreasing the transcription of HMG CoA reductase

Question 453

what enzyme do statins target. mechanism of action and what is the outcome?

Answer 453

target HMG CoA

compeitive inhibition of enzyme - transition state analoug (tetrahedral intermediate)

impair endogenous cholesterol synthesis

Question 454

step 2 of cholesterol synthesis involves the conversion of (6C) … to 5(C)….

Answer 454

mevalonate

isopentenyl pyrophospahte

Question 455

cholesterol is built up by the condensation of …. which are … carbon units in a head to tail arrangement

Answer 455

isopentenyl pyrophosphate (IPP)

5

Question 456

condensation of IPP with another IPP forms …. and this is … carbons

Answer 456

geranyl pyrophosphate

10

Question 458

condensation of geranyl pyrophosphate which is … carbons with …. forms …. which is … carbons

Answer 458

10

IPP

farnesyl pyrophosphate

15

Question 459

during step 3 of cholesterol synthesis, ultimately we get the condensation of two 15 carbon … resulting in

Answer 459

farnesyl pyrophosphate

squalene

Question 460

is an important biologic molecule as it is a precursor to many different biological molecules (e.g fat soluble vitamins, quinone electron carriers)

Answer 460

isopententyl pyrophosphate (IPP)

Question 461

in the last step (4) of cholesterol synthesis we get the conversion of …. to …. through a number of … reactions. … is then further modified resulting in cholesterol

Answer 461

squalene

lanasterol

cyclization

lanosterol

Question 462

what are the 3 main roles of cholesterol ?

Answer 462

used for steroid hormone synthesis

integral part of cell membrane - regulates its fluidity

can be transformed into bile acid/salts which aid in the digestion of lipids

Question 463

in regards to cholesterol homeostasis of hepatocytes what are mechanisms that cholesterol enters ? (4)

Answer 463

1. chylomicron remnants (exogenous dietary cholesterol)
2. VLDL remnants
3. LDL uptake
4. HDL uptake

Question 464

in regards to cholesterol homeostasis how does cholesterol exit hepatocytes ?

Answer 464

1. distribition to extrahepatic tissue by VLDL
2. bile acid/salt synthesis

Question 465

what effect does oversupply of cholesterol in hepatocytes have on LDL receptor expression ?

Answer 465

decreases expression resulting in decreased uptake of LDL from circulaiton

Question 466

what are 3 mechanisms by which hepatocytes can decrease intracellular cholesterol levels?

Answer 466

1. decrease HMG CoA reductase - rate limiting step of cholesterol synthesis
2. decrease LDL uptake by modifying the expression of LDL receptor at the plasma membrane
3. bile salt synthesis - however this is controlled by external stimulus

Question 467

liver stores cholesterol often in the form of ??

Question 468

what is the only mechanism for cholesterol elimintation from the body?

why is this mechanism not efficient in cholesterol elimination?

Answer 468

bile acid/salt synthesis

most of the bile salts are reabsorbed in the ileum of the small intestine

Question 469

deoxycholic acid is a common?

glycocholic acid and taurocholic acid are common?

Answer 469

bile acid

bile salts

Question 470

prostaglandins, thromboxanes, and leukotrienes are derived from …

these molecules are generally classified as …

Answer 470

arachadonic acid

pro-inflammatory

Question 471

derivatives of …. acid are classified as … but unlike derivatives of arachadonic are cardio protective, anti-inflammatory, and anti-carcinogenic

Answer 471

eicosanoids

eicosapentaenoic acid

Question 472

arachadonic acid is incorporated into…. at C2 of glycerol.

Answer 472

glycerophospholipids

Question 473

arachadonic acid is released from glycerophospholipds by the action of …

Answer 473

phospholipase A2

Question 474

prostaglandins are formed by the … and … of arachadonic acid by the action of … in the endoplasmic reticuulum resulting in

Answer 474

oxidation

cyclization

cyclooxygenase 1 and 2

PGH2

Question 475

thrombaxane is synthesized from … by ….

Answer 475

PGH2

thromboxane synthase

Question 476

leukotrienes are synthesized from … by a family of …. enzymes

Answer 476

arachadonic acid

lipooxygenase (LOX)

Question 477

Apirin (NSAID) is a … inhibitor

mechanisms of inhibition

Answer 477

COX-1 and 2

irreversibly acetylates serine in the active site of the enzyme

Question 478

aspirin blocks the formation of prostaglandins but also … which decreases the risk of blood clotting

Answer 478

thromboxane - thromboxane formed from PGH2 which is generated through the action of cyclooxygenases

Question 479

Vioxx was a selective …. inhibitor but was withdrawn from the market due it leading to a increases incidence of … events

Answer 479

COX-2

cardiovascular

Question 480

If glycerophospholipids contains an unsaturated fatty acid (arachadonic acid) it will be attached to carbon … of glycerol

Answer 480

2

Question 481

synthesis of phosphatidate involves the attachment of 2 activated …. to ….

Answer 481

fatty acids

Question 482

glycerol-3-phosphate can be derived from … of glycerol. this only occurs in the …

glyercol-3-phosphate can also be derived from the reduction of … which is an intermediate of …

Answer 482

phosphorylation

DHAP (dihydroxyacetone-3-Phosphate)

glycolysis

Question 483

1,2 diacylglycerolphoshate is also referred to as… and is the basic unit for glycerophospholipids

phsophatidate can also we used for the synthesis of … by removing the phosphate and esterifying a third…

Answer 483

phosphitidate

triacylglycerols

fatty acid

Question 484

… are key enzymes in the degradation of glycerophospholipids. Reaction products include … (3). These may have some novel function or be metabolized or recycled

Answer 484

mono/diacylglycerols

glycerol

free fatty acid

Question 485

… is key membrane glycerophospholipid involved in cell signalling ?

Answer 485

phosphatidyl inositol

Question 486

activated phospholipase cleaves … into … and …

… binds to receptor on the endoplasmic reticuulum leading to increased cytosolic levels.

… activates ….

Answer 486

PIP2 (phosphatidyl inositol-4,5-bisphosphate)

DAG (diacylglycerol)

Inositol-1,4,5-trisphosphate (IP3)

IP3

DAG

protein kinase C

Question 487

what is the parent compound of sphingolipids ?

Answer 487

ceramide

Question 488

… is a sphingolipid metabolite that is a mediator in many cellular events including apoptosis, proliferation, necrosis, inflammation, senescence, differentiation

Answer 488

ceramide

Question 489

sphingosine-1-phosphate is a sphingolipid …..

Answer 489

metabolite

Question 490

ceramide synthesis

step 1 add … and …

step 2 attach fatty acyl coA

Answer 490

palmitoyl CoA

Question 491

glycosphingolipid breakdown occurs in the … . this is an organelle in the cell

Answer 491

lysosome

Question 492

glycosphingolipid breakdown is most active in … tissue where they are abundant

Answer 492

neural

Question 493

…. are hydrolyzed to ceramide in … by the action of glucosidase, galactosidases, neuraminidases, hexosaminidases, sulfatases

Answer 493

glycosphingolipids

lysosome

Question 494

…. lead to growth of lysosome and eventually cellular apoptosis

Answer 494

(sphingo) lipid storage disease

sphingolipidoses

lysosomal storgage disease

Question 495

… is a disease due to defiency of beta hexosaminidase A.

Answer 495

Tay Sachs disease

Question 496

…. enzyme usually cleaves N-acetyl-galactosamine (GalNac) from glycosphingolipids and dysfunction is present in … disease

Answer 496

beta hexosaminidase A

Tay Sachs

Question 497

what are the 3 clinical subtypes of Tay Sachs disease? list from most severe to lease

Answer 497

infantile

juvenile

Adult

Question 498

Tay Sachs disease leads to an accumulation of …

Answer 498

GM2 gangliosides

Question 499

what is the main symptom of Tay Sachs disease?

Answer 499

progresive neurological impairment

Question 500

… is a disease due to deficiency of beta glucosidase leading to the accumulation of glucosylceramide

Answer 500

Gauchers disease

Question 501

Gauchers disease is caused by the defiency of … which leads to glucocerebroside accumulation

Answer 501

Beta glucosidase

Question 502

cells that have accumulation of glucosylcerebrosides are referred to …. cells

Answer 502

Gaucher

Question 503

Gauchers disease effects the …. system - cells descending from monocytes.

Answer 503

reticuloendothelial cells

Question 504

Gauchers disease can present with infiltration of…. , …megaly and skeletal and CNS complications

Answer 504

bone marrow

heaptosplenomegaly

Question 505

…. subtype of gauchers disease account for the vast majority of cases

Answer 505

type 1 - adult, non neuropathic

Question 506

type 2 and 3 gauchers disease are referred to as … and …, respectively.

Answer 506

infantile - acute neuropathic

juvenile

Question 507

Gauchers disease can be successfuly treated using ….

Answer 507

enzyme replacement therapy

Question 508

what are the two 3 carbon sugars

Answer 508

glyceraldehyde-3-phosphate

dihydroxyacetone

Question 509

function of monosaccharides?

Answer 509

fuel

cell-cell communication

structural

Question 510

sugars can be classified as … or … depending on the location of the carbonyl group

Answer 510

aldoses

ketoses

Question 511

nearly all monosaccharides found in the body are in the …. configuration

the -OH group on the penultimate carbon (last chiral carbon) is pointing to … on a fischer projection

Answer 511

D

right

Question 512

D and L glucose are … of eachother

Answer 512

enantiomers - mirror images

Question 513

steroisomers are molecules with the same structure and chemical formula but have different … at one or more … carbons

Answer 513

chirality

chiral

Question 514

what are the three most common aldohexoses found in the humman body?

these are all … of eachother

Answer 514

D glucose

D mannose

D galactose

diastereomers

Question 515

formation of the cyclic structure of carbohydrates involves -OH of the … carbon and carbon 1

Answer 515

penultimate

Question 516

monosaccharide that has a 5 member ring in cyclic form is a ….

6 member ring …

Answer 516

furanose

pyranose

Question 517

… is the carbon containing the carbonyl group of a monosaccharide

Answer 517

anomeric carbon

Question 518

cyclic forms of D glucose can exist in … and … confirmations

Answer 518

alpha (-OH of anomeric carbon below the page) and beta (-OH of anomeric carbon above the plane of the page)

Question 520

… bonds form between the anomeric carbon of a monosaccharide and an hydroxyl/amine group of another

Answer 520

glycosidic bond - can exist in alpha and beta conformation

Question 521

glycosidic bonds can be … linked or … linked

Answer 521

O

N

Question 522

what are three common dissacharides ?

Answer 522

maltose

lactose

sucrose

Question 523

maltose is made of ??

Answer 523

glucose-alpha (1,4) - glucose

Question 524

sucrose is made of ?

Answer 524

glucose - alpha (1,2) - fructose

Question 525

lactose is made of ?

Answer 525

galactose - beta (1,4) - glucose

Question 526

why do humans store glucose as a polysaccharide ?

Answer 526

reduce the osmotic pressure of stored glucose - if glucose was just free in the cytoplasm in high concentration this would cause the cell to swell and burst

Question 527

…. is the form that carbohydrates are stored in humans while plants use …. and …

Answer 527

glycogen

amylose

amylopectin

Question 528

amylose only contains …. bonds between glucose molecules therefore it is not ….

Answer 528

alpha 1-4 bonds

branched

Question 529

amylopectin contains both … and … bonds. … bonds allow amylopectin to be branched

Answer 529

alpha 1-4

alpha 1-6

alpha 1-6

Question 530

amylopectin and glycognen both contain … and … bonds, however glycogen is more highly …

Answer 530

alpha 1-4

alpha 1-6

branched

Question 531

cellulose is a homopolymer of ….

bonds between …. molecules are… which inhibits it from being broken down in the GI tract of humans. why?

Answer 531

glucose

beta 1-4 glycosidic linkages

we do posses the enzyme to break beta 1-4 glucose bonds

Question 532

beta 1-4 linkage between glucose molecules in cellulose allows it adopt a …. conformation which allows it to be a good structural molecule

Answer 532

linear

Question 533

starch, unlike cellulose is … in water and is a source of ….

Answer 533

soluble

energy

Question 534

…. is formed by the addition of an amino group to glucose. it is the precursor for the formation of glycoproteins and glycolipids. it also is found in the … fluid around joints

Answer 534

glucosamine

synonvial

Question 535

galactosamine is a constituent of …. hormones such as … and …

Answer 535

glycoprotein

FSH

LH

Question 536

glucose can be oxidized at carbon 6 resulting in a ….. functional group. this molecule is now referred to as glucuronic acid

Answer 536

carboxylic functional group

Question 537

gluronic acid is involved in the … of bile acids

Answer 537

solubilizatioin

Question 538

glucose measurment by devices has … enzyme present on the strip and therefore measures…

Answer 538

glucose oxidase

oxidated glucose

Question 539

… is a sugar found in ATP

Question 540

glucose to … is catalyzed by aldose reductase. This enzyme reduces the … group of glucose to an -OH

Answer 540

sorbitol

aldehyde

Question 541

galactose can be reduced at the anomeric carbon to form …..

…. catalyzes this reaction

Answer 541

galactilol

aldose reductase

Question 542

…. converts glucose to sorbitol

… converts sorbitol to fructose

Answer 542

aldose reductase

sorbitol dehydrogenase

Question 543

in cases of …. we get increased flux thorugh …. pathway resulting in increased … which may lead to cataracts.

Answer 543

hyperglycemia

polyol pathway

sorbitol

Question 544

increased levels of … can be toxic to a cell and lead to cataracts of the lens

Answer 544

sorbitol

Question 545

… pathway is used to convert glucose to fructose in seminal vesicles.

… is an intermediate of the pathway

Answer 545

polyol

sorbitol

Question 546

polyol pathway is implicated in … complications due to diabetes. this is due to excess …

Answer 546

microvascular

sorbitol

Question 547

aldehyde groups of sugars non-enzymatically form … with amino groups of proteins

Answer 547

schiff bases

Question 548

what is measured to determine glycemic control in diabetic patients. This is more effective than individual glucose readings

Answer 548

glycosylated hemoglobin (HbA1c)

Question 549

… are made up of repeating dissacharide units. each disaccharide unit made of a … sugar and a … sugar

Answer 549

glycosaminoglycans

uronic sugar

amino sugar

Question 550

… are long linear chains of glycosaminoglycans attached to a core protein

Answer 550

proteoglycans

Question 551

proteoglycans are a key component of …. due to its abilitty to absorb …

they can be found in .. fluid of joints, vitrous humor of eye, and cartilage

Answer 551

connective tissue (ECM)

water

Question 552

proteoglycans are synthesized in the …. and then secreted into the ….

degradation of proteoglycans involves … (intracellular organelle)

Answer 552

endoplasmic reticuulum

ECM

lysosome

Question 553

Glycoproteins

O linked - branches grow by sequential addition of monosaccharide units to …/… amino acids in associated protein

N-linked - branches grow by sequential addition of monosaccharide units to …. residue found in protein

Answer 553

serine

threonine

Asparagine

Question 554

…. are the activated form of monosaccharides which are involved in the synthesis of GAGs and glycoproteins

Answer 554

UDP-sugars

Question 555

… is a disease that is caused by impaired localization of lysosomal enzymes to the lysosome from the ER

Answer 555

I cell disease

Question 556

in I cell disease a mutation is found in …. enzyme which impairs addition of …. to enzymes which is used to target proteins to the lysosome.

Answer 556

phosphotransferase

mannose-6-phosphate

Question 557

pathophysiology of I cell disease

typical prognosis

Answer 557

lysosomes become engorged in non-digested material (seen under microscope as inclusion bodies)- this can lead to cellular apoptosis

death within first 10 years of life

Question 558

digestion of carbohydrates starts in the …. through the action of …

this enzyme break … bonds forming …

Answer 558

oral cavity

salivary amylase

glucose-alpha (1,4) - glucose

dextrins

Question 559

… is secreted from the liver and acts on starches to cleave …. bonds and like salivary amylase form ….

Answer 559

pancreatic amylase

glucose- alpha (1,4) - glucose

dextrins

Question 560

how do maltose and isomaltose differ

Answer 560

maltose: glucose -alpha (1,4) - glucose

isomaltose - alpha (1,6) - glucose

Question 561

…. is a brush border enzyme that cleaves non-reducing ends of oligosaccharides and alpha1,4 bonds of maltose to produce … monomers

Answer 561

maltase

glucose

Question 562

… is a brush border enzyme that cleaves alpha 1,6 bonds of branched oligosaccharides

Answer 562

isomaltose

Question 563

sucrase is a …. enzyme that converts … to …. and ….

Answer 563

brush border

sucrose

glucose

fructose

Question 564

…. is a brush border enzyme that converts …. to galactose and glucose

Answer 564

lactase

lactose

Question 566

what is euglycemia ?

Answer 566

normal level of blood glucose (fasting <5.6 mMol)

Question 567

what are the 3 key hormones involved in increasing blood glucose levels?

Answer 567

glucagon

cortisol

epinephrine

Question 568

what is the one hormone that decreases blood glucose levels?

Answer 568

insulin

Question 569

failure to maintain blood glucose levels above 3-3.5 mmol/L results in ….

Answer 569

neuroglycopaenia

Question 570

Insulin leads translocation of the …. glucose transporter to the cell membrane in … and … tissues

Answer 570

Glut 4

muscle

adipose

Question 571

True or False? Insulin acts on the hepatocytes of the liver and lead to increased translocatino of the Glut4 glucose transporter to the cell membrane ?

Answer 571

False - hepatocytes do not express Glut 4. they instead constitutvely express GLUt 2 transporter

Question 573

Insulin acts on the liver to stimulate …. and inhibit ….

Answer 573

glycogenesis

gluconeogenesis

Question 574

Insulin is produced in the … cells of the endocrine pancreas in response to …

Answer 574

beta

increased blood glucose after intake of a meal

Question 575

Insulin acts on adipocytes to increase …. translocation to the cell membrane and it also inhibits …. resulting in less breakdown of triglycerides

Answer 575

Glut 4

lipolysis

Question 576

…. acts on muscle cells to increase … tranlocation to the cell membrane for uptake of glucose and … also stimulares storage of glucose by promoting …

Answer 576

insulin

GLUT24

Insulin

glycogenesis

Question 577

glucagon is produced and secreted from … cells of the endocrine panceras.

glucagon stimulates breakdown of …. and release of … from adipocytes

glucagon stimulates …. and … in the liver and inhibits …

Answer 577

alpha

triacyl glycerols

fatty acids

glycogenolysis

gluconeogenesis

Question 578

the brain uses … as its primary fuel, however during starvation it can use …

the brain cannot utilize … for fuel as they are too … to cross the blood brain barrier

Answer 578

glucose

ketone bodies

fatty acids

hydrophobic

Question 579

RBCs soleyl rely on ..,. for fuel

RBCs have no … so they cannot do beta oxidation and or TCA cycle

Answer 579

glucose

mitcochondria

Question 580

liver generates but does not utilize … for energy

Answer 580

ketone bodies

Question 581

…. can only utilize glucose/anerobic glycolsys becasue they do not posses a …

Answer 581

Red blood cells

mitcochondria

Question 582

…. cells can store glucose as glycogen but cannot release glucose into circulation when blood glucose levels are low

Answer 582

muscle

Question 583

adipose tissue can take up … and … where they are converted to … and stored

Answer 583

glucose

fatty acids

triacylglycerols

Question 584

during fasting the … primarily generates energy via fatty acid oxidation

Answer 584

liver

Question 585

during fasting glycerol from fatty acid breakdown in the adipose tisue can be sent to the … and be phosphorylated and utilized in …

Answer 585

liver

gluconeogenesis

Question 586

… can switch from using glucose to … during prolonged fasting in order to spare … from occuring

Answer 586

brain

ketone bodies

muscle wasting

Question 587

…. is the only fuel that can be used by all cells of the body

Answer 587

glucose

Question 588

glucose is taken up by the brain and …. via …. trasporter. this transporter is …. independent

Answer 588

red blood cells

insulin

Question 589

… transpoter is present on hepatocytes and … cells of the pnacreas

Answer 589

Glut2

beta cells

Question 590

glucose taken up by glut2 transporter of pancreatic beta cells lead to the secretion of … into circulation

Answer 590

insulin

Question 591

during aerobic respiration/glycolysis … is reduced completely to … and …

this occurs in cells that posses a … and have sufficient … available

Answer 591

pyruvate

mitochondria

O2

Question 592

during anaerobic respiration … is reduced to … which allows for the regeneration of ….

Answer 592

pyruvate

lactate

NAD+

Question 593

glycolysis takes place in the …. of the cell

Answer 593

cytoplasm

Question 594

in the first step of glycolysis glucose is…. by the …. enzyme in the liver and …. enzyme in extrahepatic tissue. the product of this step is …

Answer 594

phosphorylated

glucokinase

hexokinase

glucose-6-phosphate

Question 595

… is the enzyme in the liver and … is the enzyme in the rest of the tissues that phoshorylates glucose to form glucose-6-phosphate

Answer 595

glucokinase

hexokinase

Question 596

…. enzyme experiences auto-feedback inhibition by its own product glucose-6-phosphate, while …. DOES NOT experience auto-feedback inhibition by its own product glucose-6-phosphate

Answer 596

hexokinase

glucokinase

Question 597

glucokinase is found not only in the liver but also in the … cells of the …

Answer 597

beta

pancreas

Question 598

the step of glycolysis catalyzed by …. represents the first committed step of glycolysis

Answer 598

phosphofructokinase (PFK)

Question 599

Phosphofructokinase catalyzes the rxn ….

this reaction requires…

Answer 599

fructose-6-phosphate to fructose-1,6-phosphate

ATP

Question 600

in non-hepatic tissue PFK is inhibited by ….

PFK is … regulated in the liver, namely by … and …

Answer 600

high ATP/ADP ration

hormonally

insulin

glucagon

Question 601

in hepatocytes insulin activates …. leads to the … of PFK2 which … it. this leads to increased production of … which … regulates PFK1 activity

Answer 601

phosphatases

dephosphorylation

activates

fructose-2,6-bisphosphate

positively

Question 602

in hepatocytes … will lead to the activation of PKA. this will … PFK2. phosphorylated PFK2 functions as a …. and will …. frutose-2,6-bisphosphate therefore reducing the activity of … in order to promote ….

Answer 602

glucagon

phosphorylate

phosphatase

dephosphorylate

PFK1

gluconeogenesis

Question 603

during the last step of glycolysis … and … are generated. the substrates for this reaction are … and …

this reaction is catalyzed by …

Answer 603

phosphoenol-pyruvate

ADP

pyruvate

ATP

pyruvate kinase

Question 604

… is an autosomal recessive disorder that is the most common cause of hemolytic anemia. the gene that is affected is …..

symptoms of this include … due to the excessive degradation of RBCs and … which is due to increased bilirubin

Answer 604

pyruvate kinase deficiency

PKLR

splenomegaly

jaundice

Question 605

why is pyruvate kinase deficiency so detrimental for red blood cells?

Answer 605

only generate ATP from glycolysis. Do not posses mitochondria to do betaoxidation and retrieve ernegy from acetyl COA

Question 606

what are the 4 fates of pyruvate ?

Answer 606

converted to alanine

converted to acetyl CoA which is can enter TCA cycle or be used for fatty acid synthesis

converted to lactate during anaerobic respiration-lack of cellular oxygen availability

converted to oxaloacetate for gluconeogenesis

Question 607

during anaerobic respiration … is reduced to … by the enzyme …

Answer 607

pyruvate

lactate

lactate dehydrogenase

Question 608

conversion of pyruvate to lactate is crucial during anaerobic respiration as it allows regeneration of … which allows glycolysis to continue to occur

Answer 608

NAD+

reduced during glycolysis to NADH

Question 609

lactate generated by anaerobic respiration can enter the blood stream and be taken up by the … and there it can be used as a substrate for ….

Answer 609

liver

gluconeogenesis

Question 610

levels of lactate in the blood above 4-5mmol/L can can ….

Answer 610

lactic acidosis

Question 611

… can result from hyoxia/poor tissue perfusion or excessice alcohol consumption. Both of these are associated with less oxidative phosphorylation

Answer 611

lactic acidosis

Question 612

reduced activity of the electron transport chain (ETC) while glycolysis is still occuring can result in increased …. this stimulates the conversion of pyruvate to … in order to refrom …

Answer 612

NADH

lactate

NAD+

Question 613

alcohol degradation leads to increased … which drives … production in order to regernate cellular ….

this is why excess alcohol consumption can lead to ….

Answer 613

NADH

lactate

NAD+

lactic acidosis

Question 614

…enzyme receives autofeedback from its product glucose-6-phosphate in the first step of glycolysis. this is not the case with the ‘equivlanet’ enzyme which is found predominantly in the liver and in the pancreas

Answer 614

hexokinase

Question 615

pyruvate kinase is active in its … form which is promoted by … (hormone)

Answer 615

dephosphorylated

Question 616

alanine inhibits …. enzyme that is involved in glycolysis

Answer 616

pyruvate kinase

Question 617

fructose-1,6-phopshate is a positive allosteric modulator of … enzyme that is involved in glycolysis

Answer 617

pyruvate kinase

Question 618

… leads to the phosphorylation of pyruvate kinase which … its activity and promotes … instead of glycolysis

Answer 618

glucagon

gluconeogenesis

Question 619

in the liver PFK1 is under … control while in non hepatic tissue PFK1 is controlled by … and …

…. is a substrate and inhibtor of PFK1

… activates PFK1

Answer 619

hormonal

ATP

AMP

ATP

AMP

Question 620

gluconeogenesis occurs in the … and to a lesser extent …. after approximately 8 hours of fasting

Answer 620

liver

kidneys

Question 621

what are 3 precursor molecules for gluconeogenesis ?

Answer 621

lactate, amino acids (e.g alanine), glycerol

Question 622

…. is not a substrate for gluconeogenesis, however oxidation of this molecule generates energy required for this process

Answer 622

acetyl CoA

Question 623

these 3 enzymes that are required for glycolysis are inactive during gluconeogenesis in order to avoid futile cycling between the two pathways

Answer 623

glucokinase

PFK1

pyruvate kinase

Question 624

during gluconeogenesis …. enzyme is inhibited so pyruvate is not converted to acetyl CoA

Answer 624

pyruvate dehydrogenase

Question 625

synthesis of 1 mole of glucose from 2 moles of pyruvate requires … moles of ATP

Answer 625

6

Question 626

the cori cycle is also referred to as the … cycle

…. released from muscle cells after glycolysis is reconverted back to … by the liver

… produced by the liver using … as a substrate is taken up by the muscle cells

Answer 626

lactic acid

lactate

glucose

glucose

lactic acid

Question 627

… and … are the main muscle derived amino acids used for gluconeogenisis

Answer 627

alanine

glutamine

Question 628

alanine can be converted to pyruvate by the action of what enzyme ?

Answer 628

alanine aminotransferase (ALT)

Question 629

the … is the only organ capable of utilizing glycerol from the breakdown of triacylglycerols

Answer 629

liver

Question 630

the … is the only organ capable of utilizing glycerol because it posseses the enzyme …

. this product can be used for … and … and can be used as an intermediate in …

Answer 630

liver

glycerol kinase

gluconeogenesis

triglyceride synthesis

glycolysis

Question 632

in the first step of gluconeogenesis pyruvate is converted to ….

this reaction utilizes the enzyme … which is found in the … of the cell

… enzyme requires …. as a cofactor

Answer 632

oxaloacetate

pyruvate carboxylase

mitochondria

Question 633

during gluconeogenesis … made from pyruvate cannot pass through the mitochondrial membrane from the mitochondrial matrix to the cytosol so it must be temorarily converted to …./….

Answer 633

malate/asparate

Question 634

in the second step of gluconeogenesis oxaloacetate is converted to ….

this reaction is catalyzed by the enzyme … which removes a … and adds a … to oxaloacetate

this steps requires energy input from ….

Answer 634

phosphoenolpyruvate

phosphoenolpyruvate carboxykinase

CO2

phosphate

GTP

Question 635

during gluconeogenesis fructose-1,6-bisphosphate is converted to …. which is catalyzed by …

Answer 635

fructose-6-phosphate

fructose-1,6-bisphosphate

Question 636

fructose-1,6-bisphosphatase is positively allosterically regulated by ….

fructose-1,6-bisphosphatase is negatively allosterically regulated by … and …

…. positively allosterically regulates phosphofructokinase1 and negatively alosterically regulates fructose-1,6-bisphosphatase

Answer 636

ATP

AMP

fructose-2,6-bisphosphate

fructose-2,6-bisphosphate

Question 637

… enzyme is a key enzyme of gluconeogenesis and glycogenolysis. It catalyzes the conversion of glucose-6-phosphate to glucose. This allows glucose to exit the hepatocytes and enter circulation

Answer 637

glucose-6-phosphatase

Question 638

regulation of gluconeogenesis

during fasting …. (hormone) levels increase and this favours gluconeogenesis

… (hormone) activates… (kinase) which will phosphorylate a number of downstream targets

decreased … (hormone) during fasting results in the release of fatty acids from adipose tissue

Answer 638

glucagon

glucagon

protein kinase A

insulin

Question 639

regulation of gluconeogenesis

pyruvate carboxylase which catalyzes the carboxylation reaction transforming pyruvate into … is positively allosterically regulated by …

transcription of the gene coding for phosphoenolpuruvate carboxykinase is positively regulated by …

pyruvate kinase is inhibited by phsphorylation by … which is activated in response to … (hormone)

glucokinase during gluconeogenesis is relatively inactive due to the relatively low … levels

Answer 639

oxaloacetate

Acetly-CoA

cAMP - binds CREBP

PKA

glucagon

glucose

Question 640

… is a cofactor that is involved in numerous carboxylation reactions (catalyzed by family of carboxylase enzymes)

… is a … carrier on the surface of carboxylase enzymes

excessive ingestion of …. which is found in egg whites has been associated with biotin deficiency

Answer 640

biotin

biotin

CO2

avidin

Question 641

… is the main storage of carbohydrate in animals. It is mainly stored in the … and … with a larger amount found in the …

Answer 641

glycogen

liver

muscle

muscle

Question 642

glycogen in muscle provides energy to muscle but does not supply glucose for … during times of fasting. this is because muscle cells do not posses … enzyme

Answer 642

circulation

glucose-6-phosphatase

Question 643

advantage of storing some energy as glycogen instead of all in triacylglycerol form is that energy cannot be yielded from fat in the same

additionally some cells only use … for energy

Answer 643

time

glucose

Question 644

…. supplies the glucose moieties used during glycogen synthesis

new glucose molecules are attached at …. ends of the preexisting glycogen molecule

at the reducing end one glucose molecule is attached to the protein … which primes glycogen synthesis

Answer 644

UDP-glucose

non-reducing

glycogenin

Question 645

glycogen synthesis

glucose is first converted to … by the enzyme … in the liver or … in the muscle

… is then coverted to … by …

glucose-1-phosphate is then converted to … by the action of … this molecule can suppply the glucose moiety for glycogen synthesis

Answer 645

glucose-6-phosphate

glucokinase

hexokinase

glucose-6-phosphate

glucose-1-phosphate

phosphoglucomutase

UDP-glucose

glucose-1-phosphate uridyl transferase

Question 646

…. is an enzyme involved in converting glucose to glycogen. It acts as a primer, by polymerizing the first few glucose molecules, after which other enzymes take over. It is a homodimer of 37-kDa subunits and is classified as a glycosyltransferase.

glycogenin is attached to the … end of the first glucose molecule

the primers which are attached to glycogenin are partially degraded … molecules

Answer 646

glycogenin

reducing

glycogen

Question 647

branches in glycogen are achievd through … bonds betwen glucose molecules

Answer 647

alpha 1-6

Question 648

branches in glycogen increase … of glycogen

braches occur roughly every …-… residues

Answer 648

solubility

7-9

Question 649

…. enzyme is responsible for creating branch in glycogen. this enzyme has two functions;

first it cleaves …. bonds

second it makes …. bonds

Answer 649

glucosyl 4:6 transferase (transferase typically break and form other bonds- move around groups)

glucose-alpha (1-4) bonds

glucose- alpha (1-6) bonds

Question 650

…. refers to the process of the breaking down of glycogen into glucose monomers

Answer 650

glycogenolysis

Question 651

… is the main enzyme for the responsible for sythesis of glycogen

this enzyme forms alpha 1-4 bonds between glucose molecules

Answer 651

glycogen synthase

Question 652

… is the key enzyme involved in the degradation of glycogen

this enzyme utilizes …. to cleave … bonds between glucose molecules producing ….

Answer 652

glycogen phosphorylase

inorganic phosphate

alpha 1-4 bonds

glucose-1-phosphate

Question 653

glycogen phosphorylase cleaves glucose molecules from glycogen until there is …. units remaining before the branch point

Answer 653

4

Question 654

besides glycogen phosphorylase which other enzyme is required for glycogenolysis ?

Answer 654

debranching enzyme

Question 655

what 2 functions does debranching have ?

Answer 655

4:4 transferase activity - transfers 3 of the remaining 4 glucose molecules to another chain

alpha 1-6 glucosidase acitvity - cleaves of remaining bond that originally was created to form a branch

Question 656

…. is the enzyme used in gluconeogenesis and glycogenolysis to release free glucose into circulation

genetic defiency of this functional enzyme leads to … disease in which patients show severe ….

Answer 656

glucose-6-phosphatase

von Gierke’s disease

hypoglycemia

Question 657

hormonal regulation of glycogen synthesis and breakdown

… acts to … glycogen synthase thereby activating it

… also acts to …. glycogen phosphorylase thereby …. it

Answer 657

insulin

dephosphorylate

insulin

dephosphorylate

inactivating

Question 658

hormonal regulation of glycogen breakdown/synthesis

glucagon leads to an intracellular increase in … by activating adenyl cyclase

… then goes into activate PKA

PKA will … glycogen synthase thereby ….

PKA will … glycogen phosphorylase thereby …

Answer 658

cAMP

cAMP

phosphorylate

inactivating

phosphorylate

activating

Question 659

fates of muscle glycogen

muscle does not contain …

glucose-1-phosphate produced by .. provides energy via glycolysis for contraction

glucose-1-phosphate is converted to glucose-6-phosphate by the enzyme …

Answer 659

glucose-6-phosphatase

glycogenolysis

phosphoglucomutase

Question 660

…. is classified as a type … glycogen storage disease

it is caused by a mutation in … enzyme

the main consequence of this is inability to release …. into circulation during fasting

biochemical testing may reveal decrease blood …, which is also reffered to as … and elevated blood ….

the second finding is due to impaired … as this enzyme is also involved in this pathway

the patient may present with an enlarged … which is clincally referred to as …

Answer 660

von Gierkes disease

1

glucose-6-phosphatase

glucose

glucose

hypoglycemia

lactate

gluconeogenesis

liver

hepatomegaly

Question 661

Coris disease is a …. disease and is classfied as type ….

it results from a mutation in the …. enzyme which is required for glycogen breakdown

this enzyme normally has 2 functions which are …. and ….

it is indistinguishable clincally from type … glycogen storage disorder

Answer 661

3

debranching enzyme

4:4 transferase activity

alpha 1-6 glucosidase activity

1 (von gierkes disease )

Question 662

… is a glycogen storage disorder that only affects muscle cells

it is classified as type …

functional form of muscle …. enzyme is absent

clincally patient present with exercise ….

it is the … severe form of glycogen storage storage disease

patient do not experience …. unlike von gierkes and corris disease

Answer 662

McArdles disease

4

glycogen phgosphorylase

intolerance

least

hypoglycemia

Question 663

glycogen storage disease

von gierkes is classfied as type …. and is due to a mutation in … enzyme

Cori’s disease is classified as type … and is due to a mutation in … enzyme

McArdles is classified as type …. and due to a mutation in …. enzyme

in which of these disease is the patient most likely to present with lactic acidosis and why?

Answer 663

1

glucose-6-phosphatase

3

glycogen debranching enzyme

4

muscle glycogen phosphorylase

von gierkes disease - glucose-6-phosphatase is involved in gluconeogenesis as well. if this is impaired pyruvate may be transformed into lactate

Question 664

…. is a unique glycogen storage disease

it is classified as type ….

is results from dusfucntional …. enzyme which is found in the …. (organelle of the cell).

this disease results in glycogen accumulation in the …. which in turn can lead to cell death

this disease not lead to …. of the blood as lysosomal glycogen breakdown is not required for maintaining blood glucose levels.

Answer 664

pompe disease

2

acid alpha-glucosidase (acid maltase)

lysosome

hypoglycemia

Question 665

the classical form of pompe disease is …. onset.

in this form patients present with … , …. , and …..

Answer 665

infantile

hepatomegaly

myopathy

hypotonia

heart defects

Question 666

Corri disease is a mutation in the … enzyme and is classified a type … glycogen storage disease.

it is characterized by the storage of structurally abnormal glycogen which is termed …..

Answer 666

debranching enzyme

type 3

limit dextrin

Question 667

… is the first sign of corris disease in children

…./…. are elevated in the blood of these patients as metabolism switches other fuel sources besides carbohydrates

Answer 667

poor muscle tone

fatty acid/ketone

Question 668

fructose to uses the …. transporter to enter enterocytes from the lumin of the small intestine.

Answer 668

GLUT5

Question 669

fructose is taken up by hepatocytes of the liver by the …. transporter

Answer 669

GlUT2

Question 670

Absorption of fructose by beta cells of the pancreas does not induce an …. response

Question 671

in tissues other than the liver fructose is acted on by the enzyme …. to become …

this is an intermediate of glycolysis

however the liver vesion of this enzyme which is called… does not recognize fructose

Answer 671

hexokinase

fructose-6-phosphate

glucokinase

Question 672

frutose metabolism in the liver

fructose is first converted to …. by the enzyme …. This is different to extra hepatic tissue where fructose is first acted on by … and converted to ….

Answer 672

fructose-1-phosphate

fructokinase

hexokinase

fructose-6-phosphate

Question 673

in the liver fructose is first converted to … by the enzyme ….

after this …. is converted to … and … by the enzyme …

…. can then be phosphorylated by triose kinase to become

Answer 673

fructokinase

fructose-1-phosphate

aldolase B

dihroxyacetone-phosphate

glyceraldehdye

glyceraldehyde-3-phosphate

Question 674

metabolism of fructose is quicker than that of glucose because the metabolism of fructose bypasses which rate limiting step of glucose metabolism in the liver?

Answer 674

phosphofructokinase1

fructose-6- phosphate to fructose-1,6-bisphosphate

Question 675

fructose is higly … when ingested with glucose because glucose stimulates … (hormone) release which inhibits gluconeogenesis and therefore fructose metabolites (G-3-P and DHP) are converted to pyruvate and acetyl CoA

Answer 675

lipogenic

insulin

Question 676

hereditary disorder of fructose metabolism usually appear …. months after birth when the baby stops ….

Answer 676

6 months

breast feeding

Question 677

fructose-1-phosphate which is made by the enzyme … is a competitive inhibitor of what enzyme ? What is the role of this enzyme

therefore accumulation of fructose-1-phosphate in hepatocytes can have what effect on blood glucose levels ?

Answer 677

fructokinase

glycogen phosphorylase

main enzyme responsible for glycogenolysis

hypoglycemia

Question 678

deficiency of this enzyme leads to elevation of blood and urine fructose but has no effect on blood glucose levels

Answer 678

fructokinase

Question 679

….. deficiency is …. and is often diagnosed accidentally when a non-glucose reducing substance is detected in the urine of a patient

Answer 679

fructokinase

assymptomatic

Question 680

deficiency of this enzyme results in a severe disorder of fructose metabolsim ?

Answer 680

aldolase B

Question 681

aldolase B deficiency leads to the acumulatin of what in liver hepatocytes ?

this product is a competitive inhibitor of what enzyme that is required for glycogenolysis ?

Answer 681

fructose-1-phosphate

glycogen phosphorylase

Question 682

infants with aldolase B deficiency are healthy until ??

Answer 682

they start to ingest fructose - this typically occurs after infants stop breastfeeding

Question 683

aldolase B deficiency not only impairs the metabolism of fructose-1-phosphate but also impairs the metabolism of … whic impairs gluconeogenesis and glycolysis

Answer 683

fructose-1,6-bisphosphate

Question 684

accumulation of fructose-1-phosphate in the cell leads to depletion of inorganic … and … which leads to increased urate prodution

Answer 684

phosphate

ATP

Question 685

accumulation of fructose-1-phosphate inhibits this …. enzyme via competitive inhibition but also by consuming inorganic … which this enzyme requires

Answer 685

glycogen phosphorylase

phosphate

Question 686

fructose -1 phosphate impairs gluconeogensis by inhibiting ….

Answer 686

glucose-6 phosphate isomerase

Question 687

along with hypoglycemia aldolase B deficiency can lead to … which is due to the fact that it inhibits gluconeogenesis

Answer 687

lactic acidosis

Question 688

what is a therapy for Pompe disease that has been approved?

Answer 688

enzyme replacement therapy - acid alpha glucosidase (acid maltase)

Question 689

patients who have aldolase B deficiency are advised to have a diet free of … and … which allows them to remain symptom free

Answer 689

fructose and sucrose

Question 690

galactose metabolism

when galactose first enters a cell it is …. by the action of ….

the resulting product is ….

Answer 690

phosphorylated

galactokinase (ubiquitous expression, not just liver)

galactose-1-phosphate

Question 691

galactose-1-phosphate reacts with … which is catalyzed by the enzyme … to form glucose-1-phosphate and ….

UDP-glucose can be regernated from UDP galactose by the enzyme….

Answer 691

UDP-glucose

galactose-1-phosphate uridyl transferase

UDP-galactose

epimerase

Question 692

glucose-1-phosphate generated from metabolism of galactose can be utilized for …. (catabolic process in muscle and liver) or transformed to … and be used for glycolysis

Answer 692

glycogenesis

glucose-6-phosphate

Question 693

classical galactosemia results from deficiency of …

this leads to the accumulation of … in the cell

clinical features of this illness include vomitting, lethary, and failure to thrive soon after breastfeeding begins. Why does this cause failure to thrive soon after breast feeding begins?

Answer 693

galactose-1-phosphate uridyl transferase

galactose-1-phosphate

lactose is a major component of breast milk. it is broke down to galactose and glucose

Question 694

…. galactosemia which leads to the accumulation of … in the cell is the more severe form as it impairs … synthesis and degradation

Answer 694

classical

galactose-1-phosphate

glycogen

Question 695

non-classical galactosemia results from the deficiency of …. enzyme

Answer 695

galactokinase

Question 696

….. leads to the accumlation of galactose which is reduced to …. by the enzyme … (also converts glucose to ….) and can lead to … of the lens of the eye

Answer 696

non-classical

galactinol

aldose reductase

sorbitol

cataracts

Question 697

…. is the main pathway for generation of ….. and ribulose-5-phosphate

Answer 697

pentose phosphate pathway

NADPH

Question 698

the Pentose phosphate pathway occurs in the … of the cell and branches from glycolysis at the level of ….

Answer 698

cytoplasm

glucose-6-phosphate

Question 699

…. produced from the …. pathway of the pentose phsphate pathway is an important reductive reagent required for fatty acid synthesis as well as glutathione reduction

Answer 699

NADPH

oxidative

Question 700

reduction of glutathione by NADPH protects against ….. damage

Answer 700

oxidative

Question 701

….. which is a product of the pentose phosphate pathway is used for the synthesis of nucleotides but can also be converted back to glycolysis intermediates …. and ….. for the generation of pyruvate

Answer 701

ribulose-5-phosphate

fructose-6-phosphate

glyceraldehyde-3-phosphate

Question 702

the …. pathway of the pentose phosphate pathway is irreversible and generates …. and …..

this pathway occurs when …. levels are low in the cell

Answer 702

oxidative

NADPH

ribulose-5-phosphate

NADPH

Question 703

…. is synthesized by two dehydrogenase complexes at the …. and … step of the oxidative pathway of the pentose phosphate pathway

Answer 703

NADPH

1st

3rd

Question 704

….. enzyme is responsible for the decarboxylation of …. to yeild the 5 carbon sugar ribulose-5-phosphate during the oxidative pathway of the pentose phosphate pathway. This reaction produces the second …. of the pathway

Answer 704

6-phosphogluconate dehydrogenase

6-phosphogluconate

NADPH

Question 705

…. is a reducing agent made from the pentose phosphate pathway

Answer 705

NADPH

Question 706

…. is important for the reduction of … which is an important anti-oxidant

Answer 706

NADPH

gluathione

Question 707

the … pathway of the pentose phosphate pathway is reversible.

it can be used for the generation of …. from ribulose-5-phosphate and vice versa

Answer 707

non-oxidative

glycolytic intermedites

Question 708

when … levels in the cell are …. the cell can use the non-oxidative pathway of the pentose phosphate pathway to synthesis ribulose-5-phosphate from …. intermediates

Answer 708

NADPH

high

glycolytic

Question 709

in non-dividing cell where requirments for nucleotides are low, the ribuolse-5-p is reconverted to …. intermediates

3 moles of ribuslose-5-phosphate converted to 2 moles of …. and 1 mole of …

in these reactions … are donors and … and … are receptors

Answer 709

glycolytic

fructose-6-phosphate

glyceraldehyde-3-phosphate

ketoses

aldoses

Question 710

… enzyme catalyses the first step of the oxidative pathway of the pentose phosphate pathway. this produces … which is an important cellular reducing agent

Answer 710

glucose-6-phosphate dehydrogenase

NADPH

Question 711

……. deficiency is a X linked chromosome disorder. Mainly affects … cells . …. observed, usually in response to a trigger (antimalarial drugs)

antimalarial drugs usually undergo a redox reaction in the cell producing a large quantity of reactive oxygen species

insufficient production of …. in affected person causes excessive oxidative damage and lysis to occur

this mutation is thought to provide natural protection against…

Answer 711

glucose-6-dehydrogenase deficiency

red blood cells

hemolytic anemia

NADPH

malaria

Question 712

…. is the site of the TCA cycle

Answer 712

matrix of the mitochondria

Question 713

… is not directly required for TCA cycle. … is required for the reoxidation of coenzymes that are … in the process of the TCA cycle

Answer 713

oxygen

oxygen

reduced

Question 714

TCA cycle overview

sequence of reactions that oxidizes …. to … and reduces nucleotides … and … to …. and …..

Answer 714

acetyl CoA

CO2

NAD+

FAD

NADH

FADH2

Question 715

…. is the common product of catabolism of fat, sugar and protein

Answer 715

acetyl CoA

Question 716

the role of the TCA is for energy production and …

Answer 716

biosynthesis

Question 717

why does NADH lead to more ATP production than FADH2 ?

Answer 717

NADH drops off electrons at complex 1 of the ETC. this complex directly pumps protons into the intermembrane space

FADH2 is dropped off at complex 2 of the ETC. this complex is not responsible for directly pumping electrons into the intermembrane space

Question 718

what role does the TCA play in gluconeogenesis ?

Answer 718

allows of the generation of ATP which is crucial to provide the energy for gluconeogenesis

Question 719

TCA cycle begins with …. and not …. as proteins and fat can contribute … to the cycle independent of ….

Answer 719

acetyl coa

pyruvate

acetyl coa

pyruvate

Question 720

primary fate of acetyl coa is … in the TCA cycle but in the cytoplasm is used for the generation of …. and …..

Answer 720

oxidation

fatty acids

cholesterol

Question 721

what are the 4 fates of pyruvate and what enzyme catalyzes each reaction ?

Answer 721

can be converted to lactate (lactate dehydrogenase)

can be converted to alanine (alanine aminotransferase)

pyruvate converted to oxalaoacetate (pyrvuate carboxylase)

can be converted to acetyl coa (pyruvate dehydrogenase)

Question 722

what is the general role of the pyruvate dehydrogenase complex?

Answer 722

convert pyruvate to acetyl-CoA

Question 723

in the first step of the pyruvate dehydrogenase complex pyruvate is …. by the …. containing enzyme ….

the end product of this reaction is ….

Answer 723

decarboxylated

thiamine pyrophosphate

pyruvate dehydroganse

acyl-TPP

Question 724

in the second step of the pyruvate dehydrogensae complex the two carbon …. is transferred onto …. and also oxidized which is catalyzed by the enzyme …

the product of this reaction is ….

Answer 724

acyl-TPP

lipoamide

dihydrolipoamide acyl transferase

acyl-lipoate

Question 725

in the last step of the pyruvate dehydrogenase complex the …. group of … is transferred to ….

….. is then oxidized by … enzyme forming which high energy electon carrier ?

… then passes its electrons to …. which can then go on to donate the electrons to the electron transport chain

Answer 725

acyl

acyl-lipoate

coenzyme A

lipoamide

dihyroxylipoyl dehydrogenase

FADH2

FADH2

NADH

Question 726

Pyruvate dehydrogenase complex and vitamins required for synthesis of pyruvate to acetyl coa

name all the cofactors, which aspect of the pyruvate dehydrogenase complex they are required for and what b vitamin they are derived from ?

Answer 726

thiamine pyrophosphate - required for pyruvate dehydrogenase enzyme. Requires thiamine (vitamin B1

coenzyme A - accepts acyl group from acyl-lipoate. requies pantothenic acid which is vitamin B5

FAD- accepts electrons from lipoamide to oxidize it- requires riboflavin which is vitamin B2

NAD - accepts electrons from FADH2. requires nicotinamide which is vitamin B3

Question 728

why are B vitamins referred to as energy supplements?

Answer 728

vitamin B1,2,3,5 are required for pyruvate dehydrogenase complex

Question 729

what are 3 negative allosteric regulators of the pyruvate dehydrogenase complex?

Answer 729

NADH, acetyl coa and ATP

Question 730

During energy excess, signalled by increased levels of … the entry of pyruvate into the TCA cycle is ….

Answer 730

ATP

prohibited

Question 731

high levels of … and … produced by fatty acid oxidation prevents … from entering the TCA cycle

therefore pyruvate can be redirected towards ….. pathway during fasting when FA oxidation is elevated

Answer 731

NADH

Acetyl-CoA

pyruvate

gluconeogenesis

Question 732

metabolism of alcohol leads to an increased level of ….

this is a … regulator of pyruvate dehydrogenase complex

therefore pyruvate may shifted towards production of ….. in order to regenerate cellular ….

in excess quantity alcohol consumption can therefore lead to ….

Answer 732

NADH

negative

lactate

NAD+

lactic acidosis

Question 733

thiamine deficiency (vitamin …) decreases ….. and …. enzyme activity

decreased enzymatic acitivity especially of … leads to shunting of pyruvate to form … resulting in ….

thiamine deficiency is often obsergved in people who are … and have …. disease

Answer 733

B1

pyruvate dehyrogenase

alpha ketoglutarate dehydrogenase

pyruvate dehydrogenase

lactate

lactic acidosis

alcoholics

Beriberi

Question 734

beriberi disease is characterized by …. deficiency

high-output congestive …. failure and …. symtpoms are strongly suggestive of beriberi disease

…. berberi - heart function effected and in some cases patients experience heart failure

….beriberi - damage nerves and can lead to a loss of muscle strength and paralysis

Answer 734

thiamine (B1)

heart

neurological

wet

dry

Question 735

… abuse can impair absorption and storage of … leading to beriberi disease

Answer 735

alcohol ‘

thiamine

Question 736

…. beriberi - caused by thiamine deficiency in the mother during pregnancy

Answer 736

infantile beriberi

Question 737

in the first step of the TCA cycle …. and … react to form ….

this reaction is catalyzed by the enzyme …

…. is a product of this reaction and also a negative allosteric inhibitor this enzyme

Answer 737

acetyl coa

oxaloacetate

citrate

citrate synthase

citrate

Question 738

citrate contains how many carbons?

Answer 738

6

Question 739

in the TCA cycle citrate is converted to …..

Answer 739

isocitrate

Question 740

in the TCA cycle isocitrate is acted on by the enzyme ….

products of this include …. ….. …… (3)

Answer 740

isocitrate dehydrogenase

NADH

CO2

alpha ketoglutarate

Question 741

alpha ketoglutarate contains how many carbons?

Answer 741

5

Question 742

in the TCA cycle alpha ketoglutarate is acted on by the enzyme …,.

this reaction also requires…

products of this reaction are… (3)

Answer 742

alpha ketoglutarate dehydrogenase

coenzyme A

NADh

CO2

succinyl coa

Question 743

succinyl CoA contains how many carbons?

Answer 743

4

Question 744

In the TCA cycle Succinyl CoA is acted on by the enzyme ….

this reaction also requires …. as a reactant

products of this reaction are ….. (3)

Answer 744

succinate thiokinase

GDP

Succinate

GTP

CoA

Question 745

in the TCA cycle Succinate is acted on by the enzyme ….

this reactions requires what else as a reactant

products of this reaction are ?

Answer 745

succinate dehydrogenase

FAD

fumarate

FADH2

Question 746

in the TCA cycle fumarate is converted to ….

Answer 746

Malate

Question 747

in the last step of the TCA cycle …. is converted to ….. and …..

the enzyme required is ….

Answer 747

malate

oxaloacetate

NADH

malate dehydrogenase

Question 748

alpha ketoglutarate requies what coenzyme to function ?

Answer 748

thiamine (vitamin B1)

Question 749

regulation of the TCA cycle

when … levels are high relative to … this signals high energy requirement for the cell and therefore need to increase flux through the TCA cycle

Answer 749

ADP

ATP

Question 750

…. activates isocitrate dehydrogenase in the TCA cycle

Answer 750

ADP

Question 751

…. is a negative regulator of the TCA cycle

it is a negative allosteric inhibitor of …. enzyme

Answer 751

NADH

isocitrate dehydrogenase

Question 752

inhibition of isocitrate dehydrogenase by ….

this leads to the accumlatin of isocitrate which favours the reformation of ….

…. is a negative allosteric inhibitor of the enzyme that formed it which is …

citrate then can be moved into the …. for ….

Answer 752

NADH

citrate

citrate

citrate synthase

cytoplasm

fatty acid synthesis

Question 754

regulation of TCA cycle

oxidation of …. by the ETC, which is a regulator of the cycle, is important for ATP production but also continued availablility of … to facilitate redox reactions of the TCA cycle

Answer 754

NADH

NAD+

Question 755

approximately ….% of amino acids for new protein synthesis recycled from protein breakdown

Answer 755

75%

Question 756

……. cannot be stored so surplus to the needs to the body are broken down

Answer 756

amino acids

Question 757

surplus …. cannot be stored - carbon skeleton recycled or oxidized for energy. …. group excreted as ….

Answer 757

amino acids

amino

urea

Question 758

…. refers to the state where amount of nitrogen consumed is matched by the amount excreted

Answer 758

nitrogen balance

Question 759

describe negative nitrogen balance?

what states can lead to a negative nitrogen balance ?

Answer 759

nitrogen excreted is greater than the amount of nitrogen consumed. Protein breakdown is occuring at a greater rate than protein synthesis (amino acids cannot be stored)

starvation - can be glucogenic or ketogenic

cachexia - severe and unintentional weight loss (cancer, congtestive heart failure, COPD)

dietary deficiency of essential amino acids - other amino acids that would have gone into making new proteins with the absent amino acids are instead degraded

Question 761

describe positive nitrogen balance?

In what situations would this occur ?

Answer 761

protein consumption is greater than protein exceretion. Protein synthesis is occuring at a higher rate than protein breakdown

pregnancy

growing child

Question 762

…. is an amino acid that can be derived from the addition of an amino group to oxaloacetate

…. is an amino acid that can be derived from the addition of an amino group to alpha ketoglutarate

Answer 762

aspartate

glutamate

Question 763

non-essential amino acids can be derived from the ….cycle, …. pathway and … pathway

Answer 763

TCA

pentose phosphate pathway

glycolytic pathway

Question 764

what is the acronym for the essential amino acids.

these must be consumed

what are the essential amino acids

Answer 764

these ten amino acids have long preserved life in man

Threonine

tryptophan

arginine

lysine

phenylalanine

leucine

isoleucine

methione

Question 765

tyrosine is considered a non-essential amino acid, however can become essential in this diseased state ?

Answer 765

phenylketouria disease

Question 766

removal of nitrogen from amino acids is a two step process

step 1: ….. with alpha ketoglutarate forming …. and …..

step 2: …. is deaminated through a … process involving NAD+

Answer 766

transamination

glutamate

alpha ketoacid

glutamate oxidative

Question 767

common amino acid/alpha keto acid pairs

alanine/….

…./oxaloacetate

glutamate/…..

Answer 767

pyruvate

aspartate

alphaketoglutarate

Question 768

… catalyze the transfer of an amino group from a amino acid to an ….

amino acid donor becomes a …. and amio acceptor (alpha ketoacid) becomes a ….

all transaminases utilize … as a cofactor. what vitamin is this derived from ?

Answer 768

transaminases

alpha ketoacid

alpha ketoacid

amino acid

PLP - pyridoxal phosphate

vitamin B6

Question 769

the most common alpha ketoacids that act as amino group acceptors in transaminase reactions are ?? (2)

Answer 769

oxaloacetate - forming asparate

alpha ketoglutarate - forming glutamate

Question 770

oxidative deamination of glutamate yields … , …. and ….

this reaction is catalyzed by …

this enzyme is reversible ? true or false

Answer 770

alpha ketoglutarate

NH4+ (ammonium)

NADH

glutamate dehydrogenase

true

Question 771

glutamate dehydrogenase is present in the … of the cell

Answer 771

mitochondrial matrix

Question 772

allosteric regulation of glutamate dehydrogenase

high …. ratio favours …. production

low … ratio favours … production

Answer 772

ATP/ADP

glutamate

ATP/ADP

alpha ketoglutarate

Question 773

amino acids can be broadly classified as … and ….

… are those whose C skeleton can be converted to intermediates which can lead to net glucose production via …. pathway

… are those who C skeleton are converted to intermediates which cannot lead to … synthesis but can lead to synthesis of …. and ….

Answer 773

glucogenic

ketogenic

glucogenic

gluconeogenesis

ketogenic

glucose

fatty acid

ketone bodies

Question 774

Fate of ammonium ion

some NH4+ utilized in … of … containing compoiunds

rest is converted to … for …

Answer 774

biosynthesis

nitrogen

urea

excretion

Question 775

extraepatic tissue can breakdown amino acids but cannot process the … group

excess ammonium is therefore converted to … and … by the enzymes …. and …. , respectively

the glucose-alanine cycle is also responsible for moving NH4+ to the liver

Answer 775

amino

glutamate

glutamine

glutamate dehydrogenase (reductive amination)

glutamine synthetase

Question 776

glucose- alanine cycle

in this cycle we get the conversion of … to … in extrahepatic tissue

in the liver … is converted to … and may be used in …. and the amino group enters the … cycle

Answer 776

pyruvate

alanine

alanine

pyruvate

urea

Question 777

overview of the urea cycle

occurs in the …. (organ)

the first phase occurs in the …

the second phase occurs in the …

amino groups enter the cycle as : (2)

…. amino groups are released as urea

Answer 777

liver

miochondria

cytoplasm

citruline

aspartate

2

Question 778

Urea cycle is regulated by the acitivity of the rate limiting enzyme ….

Answer 778

carbamoyl phosphate synthetase

Question 779

the …. is regulated by the activity of the rate limiting enzyme carbamoyl synthetase

Question 780

mitchondrial phase of the urea cycle

… and … enter the mitochondria.

….. converts glutamine to glutamate

… is acted on by … to form NH4+, NADH, and alpha ketoglutarate

NH4+, CO2 and …. are utilized in order to synthesize …. which is catalyzed by the enzyme …

…. condenses with … to form …. which is catalyzed by the enzyme

Answer 780

glutamine

glutamate

glutamate

glutamate dehyudrogenase

2 ATP

carbamoyl phosphate

carbamoyl phosphate synthetase

carbaboyl phosphate

ornitine

citruline

ornitine transcarbamoylase

Question 781

cytosolic phase of the urea cycle

in the first step … condenses with … to form …. which requires the enzyme …

this reaction is requies ….

…. is then cleaved by …. to form …. and ….

…. is ceaved into …. and …. by ….

…. can now eneter back into the mitochondria and combine with carbamoyl phosphate to form citruline and the cycle can begin again

Answer 781

citruline

aspartate

arginosuccinate

arginsuccinate synthetase

ATP

Arginosuccinate

arginine

fumarate

arginosuccinase

arginine

ornitine

urea

ornithine

Question 782

the rate limiting enzyme of the urea cycle is ….

…. is allosterically activated by … and not active wihtout the preseence of …

Answer 782

carbamoyl phosphate synthestase

carbamoyl synthestase

N -acetylglutamate

N-acetyl glutamate

Question 783

… is an allosteric activator of carbamoyl phosphate synthetase, the rate limiting step in the urea cycle

… is synthesized from … and … when cellular … are high by the enzyme….

… enzyme is allosterically activated by ….

this signals high levels of free amino acids and the need to upregulate the urea cycle

Answer 783

N-acetylglutamate

N-acetylglutamate

acetyl CoA

glutamate

glutamate

N-acetylglumatae synthase

N-acetylglutamate synthase

arginine

Question 784

clinical correlation: Urea cycle disorders

disorders of the urea potentially … because there is no … for urea synthesis

hyperammonemia can lead to …. disturbances and is also … toxic

deficits in any of the enzymes involved in the urea cycle can lead to to hyperammonemia

Answer 784

fatal

alternative pathway

acid/base

neurotoxic

Question 785

treatment for Urea cycle disorders

1. restrict ….
2. supplement diet with… (amino acid)
3. enrich diet with …
4. supplement diet
5. liver …

Answer 785

dietary protein

arginine - increase ornithine transcarbomyl transferase activity through increase ornitine. also activator of N-acetylglutmate synthase (N-aectylglutamate is a key regulator of carbamoyl phosphate synthetase)

alpha ketoacids

compounds that provide alternative means of nitrogen excretion - benzoate, phenylbuytrate

liver transplant

Question 786

…. is a metabolic disorder characterized by the inability to synthesize tyrosine from phenylalanine

this metabolic disorder results from impairement of …. enzyme

… is a cofactor for this enzyme

if left untreated it can cause progressive …. , …. damage and ….

Answer 786

phenylketouria

phenylalanine hydroxylase

tetrahydrobiopterin (BH4)

neurological degeneration

brain

seizures

Question 787

treatment of Phenylketouria

lifelong dietary … restriction and … supplementation

want level of … where protein synthesis is not affected but we do not get excess accumulation

…. is now an essential amino acid

Answer 787

phenylalanine

tyrosine

phenylalanine

tyrosine

Question 788

what are the three branched chain amino acids ?

Answer 788

valine

leucine

isoleucine

Question 789

metabolism of branched chained amino acids is inititaed in ….

there is specific brain chain ….. enzymes in … only, which convert the amino acids to …..

…. are then degraded by …. which generates….

Answer 789

muscle

aminotransferases

muscle

alpha ketoacids

branched chain alpha ketoacids dehydrogenase (BCKDH)

isovaleryl CoA

Question 790

….. disease is characterized by a deficiency of the enzyme branched chain alpha ketoacid dehydrogenase

Answer 790

maple syrup disease

Question 791

malpe syrup disease is due to a deficiency of functional ….. enzyme

Answer 791

branched chain alpha ketoacid dehydrogenase

Question 792

treatment of maple syrup disease

Dietary restriction of ….

Answer 792

branched chain amino acids to minimum level required for growth

Question 793

glutamate dehydrogenase catalyzes a reversible reaction

what condition favours the formation of glutamate from … and ….?

what condition favours the formation of … and … from glutamate ?

Answer 793

alpha ketoglutarate

NH4+

elevated cellular ATP (energy abundance) - favours anabolism, amino acid and protein synthesis

alpha ketoglutarte

NH4+

low cellular energy (high ADP or GDP) - alpha ketoglutartae can be oxidized via the TCA cycle

Question 794

…. is a key enzyme in controlling flow of nitrogen into biological molecule. …. serves as an amino group donor for the synthesis of many amino acids, nucleottides and amino sugars.

Answer 794

glutamine synthetase

glutamine

Question 795

….. enzyme is regarded as the cells nitrogen receptor

Answer 795

glutamine synthetase

Question 796

…. enzyme is subject to cumulative feedback inhibition by atleast 8 different regulators

these regulators require amino group from …. (amino acid) for synthesis

these include:

Answer 796

glutamine synthetase

glutamine

AMP

CTP

histidine

tryptophan

carbamoyl phosphate

glucosamine-6-phosphate