Cell biology and genetics Flashcards

Question 1

Q

What are kinetochores?

Answer

A

Kinetochores on chromatid centromere and are bound to microtubeles

Question 2

Q

G1 checkpoint

Answer

A

Checks for different, favorable environment nutrients proteins
If approved passes to s phase

Question 3

Q

G2 checkpoint

Answer

A

Checks if DNA is correctly replicated

Question 4

Q

Metaphase to anaphase checkpoint

Answer

A

Checks if kinetochore’s are bound to microtubeles

Question 5

Q

Cyclins

Answer

A

Expressed at specific points

Bind to CDK and activate complex

Question 6

Q

CDK

Answer

A

Inactive until bound to cyclin

Role - phosphorylase other proteins

Question 7

Q

Types of cyclin

Answer

A

Cyclin A -activates DNA replication in s phase
Cyclin B - promote assembly of spindle prepare from mitosis
Cyclin D - move cell from G0 to G1 then to S
Cyclin E - prepare for s phase

Question 8

Q

Internal checkpoint signals

Answer

A

Cellular surveillance mechanisms in cell

Question 9

Q

External checkpoint signals

Answer

A

Growth factors

Question 10

Q

G0 phase

Answer

A

When cell exits cell cycle as it doesn’t pass checkpoint

cell can stay there
go back when injured
move between stages

Question 11

Q

PDGF

Answer

A

Normally degraded after use in normal cells

in cancer cells there is too much PDGF can’t be degraded
cell continues to growth

Question 12

Q

What are telomeres?

Answer

A

Sections of DNA at the end of Chromosomes that allows them to replicate properly

Question 13

Q

What is synopsis?

Answer

A

Pairing of homologous chromosomes, where each homolog is aligned precisely with the corresponding allele of gene
- synaptonmeal complex

Question 14

Q

Crossing over

Answer

A

DNA from maternal and paternal chromatids cross over

- visible as chiasmata - exchanged DNA

Question 15

Q

Non disjunction

Answer

A

Failure of homologs in meiosis to seperate properly → aneuploidy

Question 16

Q

Aneuploidy

Answer

A

Abnormal number of chromosomes

Question 17

Q

Trisomies

Answer

A

Down syndrome -21
Patau syndrome- 13
Edwards -18

Question 18

Q

Non disjunction mitosis

Answer

A

Mosaicism-> property or state of being composed-of cells of two genetically different types

Question 19

Q

Pyrimidines

Answer

A

C,T and u (1 ring)

Question 20

Q

Purines

Answer

A

A and G (2 rings)

Question 21

Q

Transcription

Answer

A

Initiation- RNA polymerase recognises promoter + binds, RNA polymerase separates DNA strands and transcribes
Elongation- RNA polymerase continues to travel 5’ to 3’
Termination- polymerase drops off after transcription

Question 22

Q

Promoter

Question 23

Q

DNA replication enzymes

Answer

A

DNA helicase - separate strands
RNA primer allows DNA polymerase to bind
DNA polymerase - binds to DNA nucleotides at the end of RNA primer
RNA primase - attaches extra primers to gaps
Exonuclease -removes RNA primer.
DNA polymerase- RNA primer with DNA nucleotides
DNA lipase forms sugar phosphate backbone

Question 24

Q

Telemorase + reverse transcriptase

Answer

A

Use RNA molecule as a template and extends 3’ end using template

Question 25

Q

mRNA modifications

Answer

A

polyadenylation signal causes enzymes to add poly - A tail to 3’ end
5’ end 5’ Capping modified guanine (methylguanosine) nucleotide is added 5’ end (methylation)

Modifications work to:

facilitate export of mRNA to cytoplasm
protect mRNA from hydrolytic enzymes
help ribosome attach to 5’ end

Question 26

Q

Splicing mRNA

Answer

A

Catalysed by spliceosomes that recognise splice sites

remove introns
bring exons together
forms mature mRNA

Question 27

Q

Aminoacyl Trna synthatase enzyme

Answer

A

Enzyme that binds Trna and and amino acid

Question 28

Q

3 binding sites of ribosome

Answer

A

P → holds tRNA that carries growing polypeptide
A → amino acid carried
E→ exits

Question 29

Q

Translation initiation

Answer

A

Small ribosomal subunit binds with mRNA and a special initiator tRNA
small subunit moves along mRNA until it finds Aug start codon
large subunit brought in by initiation factors

Question 30

Q

Translation elongation

Answer

A

Codon recognition, peptide bond formation, translocation

A to P to E
exits to be reused

Question 31

Q

Translation termination

Answer

A

Elongation continues until mRNA stop codon reaches site A of ribosome
A site accepts release factor
release factor hydrolyses (with water) peptide chain so it is free

Question 32

Q

What is the central dogma of biology ?

Answer

A

Flow of info
DNA transcribed to RNA, translated to a protein (feedback loops)
Breakdown of processes - disease

Question 33

Q

Organelles in prokaryotes

Answer

A

Cell wall
Flagellum
70s ribosomes
Plasmids
Circular DNA

Question 34

Q

Organelles in eukaryotes

Answer

A

Mitochondria
Cell membrane
Cytoplasm
Golgi
Smooth er
Rough er
80s ribosomes
Lysosomes

Question 35

Q

Function of nucleus

Answer

A

Contains genetic into organized into chromatin

Site of ribosome biogenesis

Question 36

Q

Rough er

Answer

A

Captures mRNA begins translation → proteins

Ribosomes

Question 37

Q

Smooth er

Answer

A

Lipid production, metabolism and hormone production

Question 38

Q

Golgi

Answer

A

Post translational modification

Question 39

Q

Totipotent cell

Answer

A

Produce all cell types

Necessary to give rise to new organism

Question 40

Q

Pluripotent cell

Answer

A

Produce nearly all cell types

Form almost all of cells in 3 germ layers

Question 41

Q

Multipotent cells

Answer

A

Produce cells of closely related family

Question 42

Q

Oglioporent cells

Answer

A

Only produce a few cell types of same family

Question 43

Q

Unipotent cells

Answer

A

Can only produce one type of cell

Question 44

Q

Describe DNA helix

Answer

A

Anti parallel
Not a perfect double helix - offset major minor grooves
Grooves → allow protein interactions, important for gene expression and organisation

Question 45

Q

Central dogma

Answer

A

DNA → RNA = transcription
RNA → protein = translation
DNA → DNA = replication
RNA → DNA = reverse transcription

Question 46

Q

Conservative model of DNA replication

Answer

A

One daughter molecule contains both parent strands of DNA

Other daughter molecule contains 2 newly synthesised DNA strands

Question 47

Q

Dispersive model of DNA replication

Answer

A

Parental double helix broken into 2 double stranded segments (horizontally)
Synthesis of new double helix molecules with each strand having half new half double helix parent DNA

Question 48

Q

Semi conservative DNA replication

Answer

A

2 parental strands separate
Each strand acts as a template for new strand synthesis
DNA has one new strand and one parent strand

Question 49

Q

3 different enzymatic activities of DNA polymerase l

Answer

A

5’ to 3’ DNA polymerizing activity
3’ to 5’ Exonuclease activity
5’ to 3’ exonuclease activity

Question 50

Q

Exonuclease’

Answer

A

Destroy DNA by destroying sugar phosphate backbone

Remove nucleotides from the ends of DNA

Question 51

Q

Endonucleases

Answer

A

Can bind to middle of DNA

Question 52

Q

Describe exonuclease activity

Answer

A

Proof reading function - corrects mistakes made by polymerase

Example

DNAPI stalls if incorrect nucleotide is added as next nucleotide can’t be added
DNAPI has proofreading activity
Removes incorrect base

Question 53

Q

DNAP Ill

Answer

A

Fast, adds lots of dNTPs before dissociating

Question 54

Q

DNA packaged

Answer

A

DNA wraps round histones, proteins in cell nuclei to form a nucleosome
- DNA is packed into chromatin - genetic material composed of DNA and proteins that condense to form chromosome

Question 55

Q

Histone deacetylases

Answer

A

Enzymes that remove acetal groups from histones - allow DNA to wrap more tightly on histone

Question 56

Q

Acetylation

Answer

A

Acetal groups added to histone tails

neutralises positive charges
makes it difficult for DNA to wrap around histones
open structure?

Question 57

Q

Deacetylation

Answer

A

Acetal groups are removed from histones

exposing positively charged tails for negative charge DNA to bind to
closed structure

Question 58

Q

Defects in telomere maintenance cause…

Answer

A

Cancer and aging phenotypes

Question 59

Q

Telomeres

Answer

A

Clusters of repeated 6 pase pairs - help protect integrity of chromosomes

allow replication of extreme ends
telomerase conserve telomeres

Question 60

Q

Importance of DNA packaging

Answer

A

Protect from physical damage
environment for gene expression
allows DNA to be condensed and stored in cells

Question 61

Q

Importance of cell division

Answer

A

Development
Repair
Growin

Question 62

Q

Somatic cells

Answer

A

Non reproductive

2 sets of chromosomes = 46

Question 63

Q

Gametes

Answer

A

Reproductive cells

23 chromosomes

Question 64

Q

Mitotic chromosome

Answer

A

Made of 2 sister chromatids, with identical DNA attached via cohesions
Centromere → bind 2 sister chromatids
Kinetochore

Answer 64

A

Prophase

condensed chromosomes
centrosomes start to form microtubules (asters) move to poles

metaphase

sister chromatids position themselves on metaphase plate
kinerochores are bound to microtubeles

Anaphase

cohesion’s degraded sister chromatids separate
chromosomes pulled by microtubules to poles

Telophase + cytokinesis

nuclear membrane and nucleolus reformed
cleavage furrow

Answer 65

A

Ordered display of pairs of chromosome, from acell

Answer 66

A

2 chromosomes in a pair, carry genes controlling same inherited characteristics

Answer 67

A

Homologous chromosomes line up and separate

Answer 68

A

Chromosomes line up and chromatids separate

Answer 69

A

In meiosis 1 → each pair of chromosomes sorts maternal paternal nomolgs into daughter cells independently of other pairs

Answer 70

A

Any sperm can fuse with any ovum

Genetic variation

Answer 71

A

part of nucleus that contains proteins + RNA
Ribosome biogenesis
Ribosomal RNA

Answer 72

A

Nucleotides contain deoxyribose sugar
Base → A G C T
2 polynucleotide chains held together with hydrogen bonds between bases

Answer 73

A

Ribose sugar
Bases → A G C U
Single stranded polynucleotide

Answer 74

A

Synthesise
- mRNA 
- ribosomal RNA
- small nuclear snRNA - guide chemical modifications of other RNAs
- long non coding RNAs
- micro RNAs
Makes up 5% of cellular RNA

Answer 75

A

15% of cellular RNAs

- synthesise transfer RNA and 5s rRNA (ribosomes)

Answer 76

A

make up 80% of cellular RNA

- synthesise rRNA

Answer 77

A

Single stranded 2d clover leaf structure

anticodon complementary to mRNA
attachment site for amino acid

Answer 78

A

RNA polymerase opens up DNA and transcribes genes for tRNA
Transcript is processed properly (remove introns and modify in nucleus)
Transfer it outside nucleus to the cytoplasm
tRNA used in translation

Answer 79

A

Catalytic RNA molecules that function as enzymes that can splice RNA
Properties that allow it to act as an enzyme:
- form ③d structure due to ability to base pair with itself
- some bases in RNA contain functional groups that may participate in catalysis
- RNA may hydrogen bond with other nuckic acids

Answer 80

A

Some introns contain sequences that regulate gene expression
- alternative RNA splicing = encode more than one kind of polypeptide depending on which segments are treated as exons in splicing

Answer 81

A

Triplet code
Read 5’ to 3’
Redundant
Universal

Answer 82

A

Gene determines primary structure - determine shape

Folding makes protein functional or non functional

Answer 83

A

Free ribosomes in cytosol → synthesise proteins that function in cytosol
Bound ribosomes (to er) → make proteins of endomembrane system and proteins that are secreted by cell
- proteins destined for er or secretion - marked by single peptide
- SRP (signal recognition particle) binds to signal peptide, it escorts ribosome to receptor protein in er membrane

Proteins move to right place - due to their specific peptide sequences

Answer 84

A

Multiple ribosomes translating a single mRNA - faster

Answer 85

A

Spindle failure
one chromosome lags left out of nucleus
chromosome broken down in cytoplasm

Answer 86

A

Contains regulatory elements
Where polymerase binds to DNA
Starts transcribing at +1

Answer 87

A

Enhances expression of sections for specific genes

Answer 88

A

Cap site at 5 ‘end sequence.

Answer 89

A

Sequence recognised by transcription factor
Brings bacterial polymerase to gene
Regulatory element, place where activators bind

Answer 90

A

TATA box
Initiator -transcription start -site
Promoter proximal elements → activators and depressors
Enhancers

Answer 91

A

TBP ( tata binding proteins) recognises tata box and binds to it
TBP binds to TFII A and TFII B to form TFII D
Number of coactivators are part of TFII D to enhance transcription
TBP TFII A TFII B - bring down polymerase to right place on the gene
once polymerase is recruited, recruit TFII E F AND H

Answer 92

A

T FII

A B D E F H

Answer 93

A

Regulation of enzyme activity → bind to and inhibit enzyme and stop proceeding steps
Regulation of enzyme production

Regulate gene expression with negative feed back

Answer 94

A

Both the genes and promoter with operator in it ( on - off switch for transcription in the promoter)
- operators/ operons are controlled by repressors = bind to the operator and block RNA polymerase prevents transcription

Answer 95

A

Promotor regulatory gene - makes repressor but it is inactive by itself
When tryptophan is absent - transcription occurs

When tryptophan is present it binds to and activates repressor
Operon switched off - no transcription

Answer 96

A

’ Always on + transcribing
Only off when activated repressor binds to the operon
Example: tryptophan operon

Answer 97

A

Usually off, until inducer inactivates the repressor and turns on transcription
Example: lactose
When lactose is absent repressor is active transcription is off
When lactose is present reprossor is inactive transcription is on

Answer 98

A

Operons are switched off when repressor is active

Eg tryptophan + lactose

Answer 99

A

Stimulator proteins like cyclic amp activate transcription

When cAMP levels are high → due to low glucose levels
It binds to CRP and activates ix
Activated CRP goes to promoter drives transcription

When cAMP levels are low → due to high glucose
Not enough cAMP to bind to CRP
CRP is inactive, doesn’t drive transcription

Answer 100

A

Expression of diff genes by cells with same genome

-results in differences in cell types

Answer 101

A

Regions upstream of the promoter that activator molecules can bind to

DNA bending protein → bend + loop DNA so the enhancer region with activators is closer to the promoter
doing this means transcription complex components can be stabilised - induced transcription

Enhancer be specific, one activator specific to one promoter
Depends on availability of activators that bind to enhancers

Answer 102

A

Hormones can induce transcription - activate receptor

GR receptor bound to HSP inactiviates
when no hormone is present gr is inactive
when hormone is present it binds s to gr and removes HSP
conformational change in gr exposes NLS moves gr into nucleus
when in nucleus gr binds to DNA activate basal transcription

Answer 103

A

Change in bases in RNA c-u
Doesn’t effect DNA
Can induce an early stop codon= shorter protein

Answer 104

A

Phosphorylation - deactivates enzyme + inhibits translation

Removal of phosphate group = active continue translation

Answer 105

A

Micro RNA
Single stranded microRNA that bind to complimentary sequences in mRNA to block binding of ribosomes for translation
- binding of micro RNA can also just cause degradation of mRNA

antisense strand

1. Introduce antisense RNA strand that is complementary to target mRNA
2. Enters nucleus and finds target mRNA through complementarity
3. Form double strand RNA that is quickly degraded by enzymes

siRNA

1. SiRNA duplexes doubles RNA, goes into cells
2. Reacts with risk protein complexes
3. Target mRNAs and lead to degradation

Answer 106

A

Nucleoside sliding - conversion of ATP → ADP allows remodeler to push and slide chromatin and unwide from nucleoside
Purpose= allow polymerase to move down DNA sequence

Answer 107

A

Protein that binds to nucleosomes to regulate nucleosome activity

act as remodellers as they can dissociate nucleosome from DNA so it is more accessible to enzymes
reassemble them as new dimers or replace them with Histine Octamer

Answer 108

A

End terminals of Histone proteins that can be modified, modification can send different signals to cell which can help in gene regulation

methylation = causes nucleosomes to come closer together → compacted
combining modifications can lead to release of histones

Answer 109

A

Adding acytal group to histone tail

- neutralises positive charge, inhibits DNA wrapping

Answer 110

A

HDAC histone deacetylases enzyme → removes acetal groups
HAT histone acetal transfereases → add acetal groups

In cells there is a balance between HAT acetylation and HDAC deacytalation

inhibiting HDAC in cancers = no more deacetylation so there is more acetylation and transcription

Answer 111

A

Adding methyl groups to specific DNA bases

result in reduced I blocked transcription
can cause long term inactivation of genes
1. Methyl group is added to 5th carbon on cytosine by specific enzymes (DNMT DNA methyltransferases)
2. When this happens to cytosine near promoter areas = blocking of gene transcription downstream to promoters

Answer 112

A

Enzymes that modify histones = histone modifiers

MLL2 Histone methyltransferase is mutated in cancer
- cancer imitate histone modifiers to change transcription
MLL2 normally binds to RNA polymerase and methylates nucleosomes helping polymerase

Answer 113

A

one allele of gene expressed and the other allele is silenced

Genomic imprinting
X chromosome activation

Answer 114

A

One allele is silenced/ transcriptionally inactived by DNA methylation

Offspring express only one allele from specific imprinted genes
Imprinted gene is transmitted to all body cells during development
In next generation all imprints are raised in gamete producing allele.

Mouse example - 5.2

Answer 115

A

Both xx chromosomes are NOT expressed one is randomly inactivated in each embryonic cells
Either maternal X or paternal X are activated
- all mitotic descendants of cell with have same inactive x

Inactive X chromosome - compacts into a Barr body
once compacted most of the X chromosome genes are not expressed
In the ovary, Barr body chromosomes are reactivated and reverse back to normal active X chromosomes so gametes contain functioning X chromosome

Answer 116

A

Inheritance of traits transmitted by mechanisms not directly altering / involving the nucleotide sequence
-modifications are passed to future generations

Answer 117

A

First part of protein that exits ribosome in protein biosynthesis

Answer 118

A

Randomly derived change to nucleotide sequence of the genetic material of an organism

To be phenotypically effective mutations must alter gene regulation or actions

Answer 119

A

Spontaneous
-caused by chernial instability of DNA

Environmental
- DNA clamage from environment, physical (radiation) or chemical mutagens

Genetic events

rearrangements - recombination of DNA
DNA replication

Answer 120

A

P53 works at g1 checkpoint and detects DNA damage
stops cell cycle if DNA is damaged to allow time for repair
P53 activates the DNA repair system and induces transcription of p21
p21 prevents cyclin and CDK complex formation
DNA can’t move to S phase for replication

Answer 121

A

If cells are damaged too much - repair can’t cope with amount of DNA damage

apoptosis
necrosis

Answer 122

A

Organised / intentional cell death outer membrane is still intact and it can still function

Deactivating bcl-1 (protein that inhibits apoptosis) through well controlled chain of enzyme reactions
Catabolic processes begin throughout cell - enzyme digests cytosolic components, fragment nuclear Dna, cysteine proteases target proteins
Cell is re packaged for safe removal cell shrinks and fragments into stall membrane bound apoptic bodies
Compacted cell is phagocytized by adjoining cells

Answer 123

A

caused by physical disruption to cell through injury, toxins, deprivation
1. bacteria secrete toxins that disrupt cell function and structure
2. Cell loses control, swelling organelles, clumped chromatin, eventually bursts
3. Cytotoxic cellular components spill out from membrane

Issue= tissue damage + inflammation

Answer 124

A

DNA is relatively unstable
bond between sugar + base is unstable - random loss of bases
can happen to hundreds, thousands bases

Answer 125

A

Removal of an amino group from a base

induced by attack by free radicals chemical mutagens eg nitrous acid
can cause base change c→u

Answer 126

A

Addition of 0, 02, hooh or oh group to a base

these oxygen species are reactive as they try to stick to something when they hit molecules they attach to it and change chemical structure
affect pairing ability of DNA

Answer 127

A

CPD + pyrimidine pyrimidone 6-4 photoproducts

photons reach cells, skin cells are exposed
Photon cause 2 neighouring bases to be linked by a covalent bond
cause conformational change in DNA
replication can’t occur until bond is removed

Answer 128

A

Smoking

insertion and covalent bond formation between benzo[a]pyrene and DNA in middle of DNA ladder
disrupts base pairing

Answer 129

A

Deposits energy directly in the molecule to break covalent bonds or hycrolyzes water into reactive oxygen molecules that attack DNA

create single strand breaks
base damage
crosslinks
DNA double stranded breaks
Multiple damage sites

Answer 130

A

Direct repair ( reversal of damage )

Excision and resynthesis of damaged region (only one damaged DNA strand)

Strand break repair (breaks in backbone, both strands)

Answer 131

A

Photo reactivation - directly reverses formation of pyridine dimers (bonds where structure of DNA helix is kinked twist )
→ uses enzyme photolyase - absorbs energy from uv light to use in catalysis breaking the covalent bond

Only occurs in prokaryotes

Answer 132

A

Takes advantage of double stranded DNA

3 pathways:

DNA mismatch repair
base excision repair - remove damaged bases
nucleotide excision repair - use undamaged DNA as a template

Principles

Protein scans DNA for kink
Binds to it and removes damage section of strand reveals single stranded region
Single stranded region is used as a template to replace damage strand

Answer 133

A

Break backbone= must join ends correctly to avoid mutation

ends recognised by proteins
Proteins realign and resynthesises some nucleotides if ends aren’t compatible
Ligase joins strands together

Answer 134

A

Repair DNA by conducting excision and replication on the spot
- re replicate the strand correctly
DNAP can reverse direction of replication and fix damage

Answer 135

A

When DNA double strand breaks

- based on ability of single DNA strands to find regions of near perfect homology elsewhere in genome

Answer 136

A

if DNA damage is efficiently repaired = non problematic viable cell
if DNA can not be repaired due to too much damage - cell death
if DNA undergoes mis repair Where repair is not sufficient - mutation

Answer 137

A

Mutation in coding sequence

Answer 138

A

Mutation in non coding sequence

Answer 139

A

Erythemia = skin reddening
necrosis of exposed tissue
eye irritation
increased incidences of leukemic

Radiation does not produce new unique mutation but simply increases incidence of same mutations that occur spontaneously

Answer 140

A

Bond breaks occur either:

directly = by direct ionisation of biomolecule
indirectly= through ionization of water and formation of damaging radicals

Answer 141

A

treat cancers
proven benefit - long term survival
damage cancerous cells
imaging delivery of treatment

Answer 142

A

Mutation that only affects a single nucleotide of a nucleic acid

deletion
insertion
substitution

Answer 143

A

Change one base for another

Transition

switch pyrimidine for another pyrimdine (c and t)
switch purine for another purine (a and g)

Transversion

switch purine for pyrimidine
switch pyrimidine for purine

Answer 144

A

Frameshift - change in the codon change one base in reading frame

Nonsense- introduce premature stop codon

Missense- change entire amino acid, caused by change in one base

Answer 145

A

Change in one nucleotide in DNA sequence
- change from glutamic acid to valine
changes folding of haemoglobin
Chromosome 11

Answer 146

A

Dwarfism
Adenine replaces guanine
Arginine produced instead of glycine
Missense mutation in FGFR3 on chromosome 4
- cartilage can’t fully develop into bone

Answer 147

A

Nonsense mutation - substitute g to a which results in premature stop codon
Chromosome 12
PKu=phenylalanine build up - neurological defects

Answer 148

A

Insert or delete any number of bases ends isn’t a multiple of 3= frame shift

Answer 149

A

. Mutation in ctfr gene - Cf transmembrane conductance regulator gene
- causes trick secretions

mutation of F508 deletion of one amino acid phenylalanine in position 508

Cloned by positional cloning strategy - 6.2 notes

Answer 150

A

Cf is good for gene therapy because it is:

a single gene defect
recessive condition
accessible for treatment (pathology in lung)
progressive disease

Answer 151

A

large number progeny observe segregation and recombination
well controlled environment
fast
similarity bew human t mice

Answer 152

A

Normal genes that help cell grow

Answer 153

A

Any gene that causes cancer

Answer 154

A

Variation in the number of repeats between people

Answer 155

A

Satellite DNA
Tandem repeats
Interspersed repeats

Answer 156

A

→ type of repetitive DNA with unclear function
2 classes:

alpha repeats = sequence of 171 bp (long) often repeats in clusters up to several Mb long
beta repeats = sequence of 68 bp (smaller) often in clusters of 100 kB to several mb

Answer 157

A

→ repetitive sequence make up 10% of genome used for positional cloning, genetic markers

Mini satellites - short tandem repeats 2-5 bp overall length 70-200 bp
micro satellites = near telomeres,20 bp core sequence, 1-390 kb
Macro satellites = near centromeres and telomeres megabases long

Answer 158

A

Up to 5-20% of genome

SINEs -less than 500 bp, short interspersed nuclear elements
LINEs - more than 500 bp, can contain pseudogenes and reverse transcriptase like genes

Answer 159

A

Necessary for assembly of human genome

rearrangement of genome
duplication and point mutations are key to genomes

Answer 160

A

Telomeres are repetitive DNA at ends of chromosomes

- protect chromosome ends from degradation

Answer 161

A

Variable number tandem repeats= short DNA sequences repeated in tandem adjacent to one another

variation in no. Of times sequence is repeated in a given locus
variability is specific to each person (based on inheritance)

DNA fingerprinting
-if probe is made from VNTR - the size of the pattern of the fragments is the DNA fingerprint

Restriction enzyme cuts either side of VNTR

VNTR polymorphism
used in DNA fingerprinting

Answer 162

A

Restriction enzymes → cut specific DNA sequences
- can only cleave specific 4-6 bp palindromic sequences

Bacteria

Bacterial DNA is methylated
Bacterial cells have methylase activity with the same sequence specificity
Bacterial re cannot cleave host DNA as it is methylated
But if same sequence is present in viral DNA (unmethylated) it will be cleaved

Answer 163

A

RE will cleave unmethylated DNA → produce sticky ends (overhanging ends offset from eachother)

2 samples cleaved w same RE will have complementary sticky ends
can be realigned and ligated with DNA ligase to give recombinant DNA

Answer 164

A

SSLPs (simple sequence length polymorphisms) are used as genetic markers in PCR

they are repeated sequences over varying base lengths
difference in number of repeats between individuals

Answer 165

A

Cut DNA from donors with restriction enzymes
reveal polymorphism due to presence or absence of restriction site
Resulting fragment will be of different lengths in different people

Answer 166

A

Use complementarity between probe and target → hybrid probe target complex to identify molecules of interest in complex mixtures

Answer 167

A

DNA-DNA

single stranded ssDNA = probe
ssDNA forms double stranded base paired hybrid with it’s target

DNA - RNA
- ssDNA probe forms double stranded base paired hybrid with RNA

Protein-Protein

antibody = probe
antibody can form complex with a target protein if the antibody’s antigen binding site can bind to target protein

Answer 168

A

probe only binds to targets with complementary sequence/shape
reactions occur in the presencence of large quantities of molecules that are similar but not identical to the target.

Answer 169

A

Form of procedure used to identify specific sequences of DNA

fragments are separated on a gel
transferred directly to a second medium hybridization

Answer 170

A

Cut with restriction enzymes + probed with radioactive DNA

- used in genomics

Answer 171

A

probed with radioactive DNA or RNA

- used in transcriptomics

Answer 172

A

Protein probed with radioactive or erzymatically tagged antibodies
- in proteomics

Answer 173

A

Separate molecules on basis of molecular weight - gel electrophoresis
Transfer separated molecules from gel → solid support (blotting)
Hybridization - to detect target sequence using labelleled probes and detecting probe target hybrids

Answer 174

A

→ making multiple copies of DNA sequence

Initiation: polymerase that require heat activation

Denaturation: heat to 95° to denature DNA and break h bonds
Annealing: temperature lowered to 50 to 70 degrees, primers anneal to target DNA sequence
Extension + elongation: raise temp to 72°, enzyme tag polymerase bind to primed sequence and adds nucleotides to synthesise new DNA strand

Answer 175

A

Design a pair of primers flank a region of DNA that is of interest.
Can cause RSP restriction site polymorphism = caused when PCR amplifiers vary in size if primers can snow that DNA region snows size variation

Answer 176

A

helps with identification
appearance reflects level of chromatin condensation
dark + light patches

Answer 177

A

Short arm =p

Long arm=q

Answer 178

A

Telocentric - no p arms
Accrocentric - small p arms
Submetacentric - p arms are shorter than q aims
Metacentric - centromere in middle arms are in the same place

Answer 179

A

→ method of gaining banding pattern reproduce able for chromosome analysis

Treat with trypsin
Stain with Giesma
Viewedby light microscope

Answer 180

A

Branch of genetics about how chromosomes relate to cell behaviour
-Specifically in mitosis /meiosis

Cytogenetic process:

culture the sample
Harvest sample induce mitosis to obtain metaphase
Prepare bands
Analyse preparations -number of chromosomes and banding

Answer 181

A

Anomalies during embryogenesis

- all tissues hold same anomaly, error present in embryo

Answer 182

A

Anomalies in cancer

- one organ is involved, other tissues are normal

Answer 183

A

Exchange of material between 2 chromosomes

balanced= no loss or gain of material - phenotypically normal
unbalanced - loss or gain of material - lead to anomalies

Answer 184

A

Between 2 Acrocentric chromosomes

loss of sequences from p arms of chromosomes = lost fragment
but amount of DNA lost is negligible
chromosomes break. And rejoin, 2 q arms fused= robersonian chromosome

Answer 185

A

Trisomy 18

Failure of organs systems

Answer 186

A

Trisomy 13

Congenital abnormalities, polydactyl

Answer 187

A

Monosamy - one X chromosome

Sterile short female

Answer 188

A

Trisomy 47 extra X chromosome XXY

Fertile low iq

Answer 189

A

Trisomy 47 extra X XXY

Sterile male, more woman like in appearance

Answer 190

A

Trisomy 47

Sterile violent more manly male

Answer 191

A

Amine group
Carboxyl group
H atom
Distinctive r group

Answer 192

A

What remains of amino acid after it has been joined by a peptide bond to form protein
Coo-
Nh3+

Answer 193

A

Only a few amino acids in length

Answer 194

A

Many amino acids

Answer 195

A

Protonated
Nh3+
Cooh

Answer 196

A

Deprotonated
Coo-
NH2

Answer 197

A

pH = pka + log [A-]/[HA]

When [HA] = [A-]
ph = pka

Answer 198

A

Positive and negative charges are equal → no net charge

pH = pka

Answer 199

A

Non polar don’t easily dissolve in water

Polar easily dissolve in water

Answer 200

A

Aliphatic= no rings

Aromatic=rings

Answer 201

A

R groups - positive= higher pk

High ph - basic solution - less H atoms - deprotonated

Answer 202

A

Negative r groups- lower pk

Low ph -acidic - lots of hydrogen - protonated

Answer 203

A

If ph < pk = protonated

If ph > pk- deprotonated

Answer 204

A

Peptide bonds are planar - restrict rotation of bond

Favours trans formation - more free

Answer 205

A

Basic protein isoelectric point > 7 - greater than 7

Acidic protein isoelectric point <7 - less than 7

Answer 206

A

If ph is less than pl - protonated

If ph is more than pI = deprotonated

Answer 207

A

3.6 amino acids in a turn
H bonds between every 4th amino acid btw carbonyl on one amino acid and amine on another
Pro and Gly - helix breakers

Answer 208

A

Can be parallel or anti parallel (more stable, optimal H bond pattern)

Answer 209

A

Improperly folded → toxic protein clump - non functional inhibits processes

Answer 210

A

Takes place

Co translational= while being translated
post translational - after translation finished

Answer 211

A

catalysis, regulation cact us enzymes)
several types of secondary structure
compact shape

Answer 212

A

Support, shape protection
single type of repeating secondary structure
long strands or sheets eg collagen

Answer 213

A

Makes up several connective tissue

triple helical arrangement with glycine at every 3rd position
glycine = smallest amino acid, sticks between helixes to stabilize

Answer 214

A

Linked together with crosslinks - small fibres
Collagen formed from tropocollagen fibres
Triple helix stabilised by one direct inter chain h bond as well as water mediated h bond

Answer 215

A

Domains - part of polypeptide chain that fold into a distinct shape with specific rou

Water soluble proteins

hydrophobic side chains = inside protein
hydropnillic side chains - outside protein

Answer 216

A

Allow transport (of water soluble molecules) due to pore present in middle of protein

Hydrophilic chains = inside
Hydrophobic chain -outside

Answer 217

A

Protein complexes formed by different types of polypeptide chains
Diverse

Answer 218

A

-protein complexes formed by assembly of multiple copies of a single type of polypeptide chain

Answer 219

A

When DNA bound to p53 - increases DNA binding activity
Low binding= survival
High binding = cell death., high binding is due to mutations in p53 which increase DNA binding = too much transcription → cancer

Tetrameric p53 = 4 subunits bind to DNA act as transcription factor
Tetrameric transcription is beneficial as error in one subunit = decrease binding affinity of complex

Answer 220

A

If protein is correctly folded it goes to Golgi
Misfolded protein moves into intercellular space to go to ubiquitin proteasome which degrades it
- chaperones use ATP to help protein fold into correct shape

Answer 221

A

CF

- alzhemners - aggregated tau proteins - neural dysfunction

Answer 222

A

Gives an estimate of how distant they are on the chromosome - the more distant they are the more likely that during recombination regions will be recombined
- measured by genotyping individuals in a family looking at recombination of both chromosomes

Answer 223

A

1 unit of recombination = 1 cM centi Morgan
-observed in 1 out of every 100 meiosis

1cM is about 1 million bases

If distance is close = will not recombine

Answer 224

A

Autosomal dominant
Autosomal recessive
X linked dominant
X linked recessive
Y linked

Answer 225

A

Affected individual = one affected parent
Present in every generation
Males + females are equally likely to be affected
Transmitted by either sex
Child of affected individual = 50% chance of being affected

Eg. Achondroplasia (FGFR3) Marfan syndrome (FBN1) Huntington’s(HD protein CAG repeat)

Answer 226

A

Both genders affected
Both parents affected = all children affected
Normally children can be affected but parents are not
Affected individual t normal partner - normal chil

Answer 227

A

Mainly affects males
Affected males are born to unaffected parents
Transmitted to males from mother
Only one mutant X needed

Answer 228

A

Sex affected
Usually one affected parent
Affected mall only has affected daughters

Answer 229

A

Only males affected

Affected males - affected father

Answer 230

A

Intermediate genotypes produce an intermediate phenotype

Answer 231

A

Mitochondria is inherited by mother

Severity of phenotype - depends on type of mutation, prevalence of abnormal mitochondria

Answer 232

A

Donor egg, mother egg, father sperm

Maternal spindle transfer
1. genetic info from donor egg removed
2. Genetic info from mom w/o mitochondrial defects inserted into donor egg
3. Egg is free from defective gene
4 fertilised

Pro nuclear transfer

Mothers egg fertilised by sperm
Embryo has maternal mitochondria with defective genes parental DNA exists as pronuclei in cell
Pro nuclei removed from cell and added to donor cell with normal mitochondria

Answer 233

A

Loose - more branched spaced out

Fibrous- striated and compacted

Answer 234

A

Mutation in collagen 2 or 1

small glycine substituted for bulkier amino acid = cysteine
alter collagen structure - weak and breakable

Answer 235

A

In cells of fibroblasts

Signal sequence on polypeptide chain is used to guide chain to er
Signal sequence is cleaved
Hydroxylation of proline to hydroxyl proline using vitamin c
Add sugar molecules - glycosylation
Modifying the amino acid - triple helix

N + C terminals held together by disulfide bonds

Answer 236

A

Collagen fibres spread widely

Elastic fibres

Answer 237

A

Collagen fibres packed tightly

See fibroblasts and nuclei

Answer 238

A

Only amino acid with a side chain small enough to fit in the middle of the tropocollagen
Must abundant in tropocollagen

Answer 239

A

Occurs mainly in the cells of fibroblasts

Synthesised in the cell in the rough er
Collagen passes to Golgi
Collagen is transported outside cell - exocytosis
Collagen molecules undergo more polymerization to form final collagen fibres

Answer 240

A

Signal sequence guides polypeptide chain to er

signal sequence is cleaved when it enters the er
hydroxylaction of proline dependent on vitamin c and asorbcate
after hydroxylation there is glycosylation adding sugar molecules occurs in Golgi
after modifications the helix twists with 2 more helices
2 terminals N and C -
C terminals held together by disulfide bonds

Answer 241

A

In extracellular space pro collagen peptidase cleave preform peptide on procollagen =tropocolgen
- process removes N and C terminals

Answer 242

A

cross links between tropocollagen molecules are made by Lysol oxidase
tropocollagen molecules bound together = collagen fibrils

Answer 243

A

Lysol oxidase acts on 2 lysine residues to form cross links

requires vitamin B6 and copper ions for activity
adds Aldol cross linking that makes collagen stronger

Answer 244

A

Deficiency of vitamin c and asorbic acid

- symptoms: fatigue, weakness, poor wound healing, anaemia and gum disease

Answer 245

A

Deficiency of Lysol oxidase - bonding is less strong= stretchy skin
Or mutation in collagen type 5
- inherited connective tissue disorder

Answer 246

A

Breaking peptide bonds to remove part of protein

Answer 247

A

Addition of functional groups to amino acid residues

Answer 248

A

Synthesised by ribosomes on rough er or free ribosomes in cytosol → go to cytosol or post translational import into organelles

co translational insertion - synthesis of of polypeptides by ribosomes at border of so protein is contained in er

Answer 249

A

Intrinsic signal - like an address that belongs naturally to protein
receptor - that recognises signal and directs it to correct membrane
translocation machinery - helps translocation
energy ATP to transfer protein

Answer 250

A

Protein targeting sequence- SKL serine lysine leucine

Signal intrinsic to protein = SKL signal on c terminus of protein recognised by receptor and binds to it
Receptor PTS1R takes protein catalase tetramer to the Pex14p receptor on peroxisome membrane
Pex14p receptor on peroxisome membrane helps transport receptor protein complex into cell
- first receptor dissociates from protein leaves through membrane

4.PTS1R receptor is moved through cell using ATP

Answer 251

A

PTS1R receptor- binds to protein intrinsic signal
SKL - protein targeting recognition sequence
Pex14p receptor- on peroxisome membrane

Answer 252

A

Regulated secretion

Endocrine cells - secrete hormones
Exocrine cells - secrete digestive juices
Neurocrine cells - secrete neurotransmitters

Unregulated
- constitutive secretion - secrete proteins continuously like collagen

Answer 253

A

Protein with signal sequence
chaperone that carries protein to protein translocater complex
signal peptidases to cleave signal from protein
ATP

Answer 254

A

Proteins translated in er lumen
folded into 3d structure
Go from er → Golgi
Continues post translational modifications in Golgi
proteins put into secretory vesicles

Answer 255

A

extracellular proteins
membrane proteins
vesicular proteins

Answer 256

A

Protein translated from mRNA -signal sequence translated first
Signal sequence recognised by signal recognition peptide - binds to ribosome bringing it to er membrane
Ribsome translates protein into er lumen

Answer 257

A

same process as secretory except:

halfway through translation, there is an anchor sequence that allows hydrophobic amino acids to associate with membrane
then rest of membrane is synthesised

Answer 258

A

Insert proteins into membranes
specific proteolytic cleavage
proper folding of proteins
assembly of multi subunit proteins
hydroxylation of selected lys and pro residues
glycosylation
formation of disulfide bonds

Answer 259

A

Sugars (glucose, galactose etc) are added on asparagine side chain

reaction involves amino group - that is why it is called n-linked
happens in er

Answer 260

A

Allows proper protein folding
increases protein stability
facilitates interactions with other molecules
deficiency - severe inherited human diseases, congenital disorders

Answer 261

A

→ SH groups in two cysteine residues form disulfide bond

facilitated by disulphide isomerase
formed in er lumen
helps protein stability

Answer 262

A

Protein may be trapped in misfolded conformation
protein may contain mutation resulting in misfolding
protein may be associated incorrectly with other subunits

Answer 263

A

Attempt to correct misfolded protein:

retain unfolded proteins in er
act as sensors to monitor extent of misfolding= mediate increased transcription of chaperones, mediate reduction in translation

Answer 264

A

Protein returns to cytosol for degradation

- proteins can accumulate at toxic levels in er = disease

Answer 265

A

Adding sugar to hydroxyl group of serine, threonine

Answer 266

A

Affect substrate and product concentration

2. Change the enzyme conformation (Shape)

Answer 267

A

Allosteric regulation = changing enzyme shape prevent substrate binding
Covalent modification = blocking active site alter shape
Proteolytic cleavage = removing precursor element of protein changes its shape so it interacts with substrate

Answer 268

A

→ building up then secreting protein stores

change rate of protein synthesis - now much protein made
change rate of protein degradation

Answer 269

A

different forms of the same enzyme that have different kinetic properties
active site has different conformation, modified it is even more specific to substrate, so there is better binding efficacy
catalyse same chemical reaction

Answer 270

A

→ organic non protein compound that catalyse a reaction

not enzymes
limiting coenzyme availability can regulate enzyme activity

Answer 271

A

→ • Product can become limiting – accumulation of the product of a reaction inhibits the forward reaction (the enzyme)

Eg Glucose-6-phosphate inhibits hexokinase activity = negative feedback, by either competitive binding or allosteric regulation

Answer 272

A

→ allosteric enzymes snow a sigmoidal relationship between rate and substrate conc

affects initial velocity of the reaction as substrate conc may be high but the enzyme shape is not optimal to bind to substrate
Vmax stays the same but Km differs

Answer 273

A

Tense state (T) - low affinity to substrate, closed up like a fist
Relaxed State (R) - high affinity to substrate, more open

Answer 274

A

Inhibitor/activator binds to another region on the enzyme that isn’t the active site
causes conformational change
Either prevents enzyme binding or promotes enzyme binding

Answer 275

A

Prevent enzymes binding to substrate

Increase proportion of enzymes in the t state

Answer 276

A

Promote binding of enzyme to substrate

Increase proportion of enzymes in r state

Answer 277

A

→ allosterically regulated enzyme that sets pace for glycolysis

Allosteric inhibitors: ATP, citrate and hydrogen ions limit enzyme activity when ATP is high
Allosteric activators: AMP fructose-2,6-biphosphate

Answer 278

A

PH= pka + log[A-]/[HA]

Answer 279

A

Acid dissociation constant

Answer 280

A

Resist large ph changes

equilibrium maintained
added acids h+ are neutralised by base A- to give acid ha
added bases oh- are neutralised by acid HA converted to base a-

Answer 281

A

Makes protein negatively charged due to added phosphate groups from ATP → change binding ability

phosphoryl groups can make h bonds = affects binding
rates of phosphorylation / dephosphorylation can be adjusted by activating / deactivating enzymes

Answer 282

A

Adds phosphate groups to protein

- transfer terminal phosphate from ATP to OH of ser, try, thr

Answer 283

A

Remove phosphate groups

- reverse effects of kinases by catalysing the removal of phosphoryl groups from protein

Answer 284

A

-> Takes small amount activation and produces amplification of initial signal -enzyme cascade

Protein kinase is phosphorylated and activated
phosphorylates and activate, another protein kinase
Chain continues activating many protein

Answer 285

A

When glycogen is broken down glycogen synthesis stops

Protein kinase a phosphorylates and activates phosphorylase kinase
Phosphorylase kinase activates phosphorylase a → breakdown of glycogen
phosphorylase kinase phosphorylates glycogen synthase → inactivation of glycogen synthase so glycogen can’t be synthesised

Answer 286

A

protein kinase a
phosphorylase kinase
phosphorylase kinase a

Answer 287

A

Phosphorylase kinase

Glycogen synthase

Answer 288

A

Used to activate an enzyme

start with inactive form of enzyme -zymoyen
Enzyme is activated through proteolytic cleavage
Releases active form of the enzyme

Answer 289

A

Inactive form of the enzyme

Answer 290

A

Blood clotting - cascade of proteolytic activation
protein hormones - inactive precursors
developmental processes - activation of zymogens for tissue remodelling
apoptosis - mediated by proteolytic enzymes (capases) synthesised in inactive (procapase) form

Answer 291

A

Chymotrypsin - digestive enzyme that hydrolyse proteins in small intestine
Chymotrysingen= zymogen stored in membrane bound vesicles- zymogen granules released when lumen of intestine are activated by trypsin

Trypsin is the enzyme that cleaves chymotry psinogen to activate it → chymotrypsin
Trysin cuts between Arg15 and lle16 = pi- chymotrypsin l2 amino acid chains)
Further modification = alpha-ct (3 amino acid chain)

Answer 292

A

-> activates pancreatic zymogens

Trypsinogen = trypsin zymogen

activated by enteropeptidase membrane bound protease in lining of duodenum
active trypsin can autocatalytically activate trypsinogen – therefore amplification of signal from a few molecules of trypsin

Answer 293

A

More trypsin activates proenteropeptidase which activates enteropeptidase with activates trypsinogen → trypsin

Answer 294

A

Plasma protein that inhibits multiple proteases including chymotrypsin and trypsin

Deficiency of α1-antitrypsin = emphysema

prevents and inhibits trypsin from being activated
trypsin goes unregulated and continuously activates proelastase → elastase that destroys alveolar walls

Answer 295

A

Intrinsic → caused by damaged endothelial linking of blood cells - promotes binding of factor xIl
- insides circulatory system

Extrinsic → trauma release of tissue factor iii from tissue surrounding capillary
-outside circulatory system

Both pathways lead to factor X activation

Answer 296

A

Factor X activation leads to thrombin activation
- thrombin - fibrin production = causes clot
Very small amounts of factors XII and III cause clotting

Answer 297

A

Activated by phosphorylation and proteolytic cleavage of different factors
- once fibrin production becomes cross linked and forms hard blood clot

Answer 298

A

2 Kringle domains = protect actual thrombin and keep it in inactive form
protease function (actual thrombin part) is kept in c terminal domain
gla residues - target appropriate sites for activation, so clots occur in the right place

Answer 299

A

→ addition of carboxyl groups to glutamate residues = carboxyglutamate gla
- using vitamin k

it allows amino acid to interact with sites of damage and brings together clotting factors with calcium binding.

Answer 300

A

effects vitamin k and Inhibits process of carboxylation (gla formation)
thins the blood, used for people at risk of heart attack or stroke

Answer 301

A

Calcium only binds to carboxylated Ga residues as they have calcium binding sites

prothrombin next to site of damage will bind to calcium and activate= thrombin
No carboxylation of glutamate - no thrombin activation, no fibrin, no clot

Answer 302

A

2 sets of tripeptides alpha, beta and gamma joined at N terminal by disulphide bonds

Answer 303

A

Thrombin cleaves fibrinopeptides A and B from central globular domains of fibrinogen
Globular domains at c terminal ends of beta and gamma chains interact with exposed sequences at N termini of cleaved beta and gamma chains → fibrin clot or mesh
Multiple subunits come together

Answer 304

A

Factor 13 facilitates cross linking between molecules to produce mesh structure - amide bonds between side chains of lysine and glutamate residues
Cross linking reaction catalysed by:
- transglutaminase
- procransglutaminase

Answer 305

A

- Need constant activation of clotting pathway → ensure sufficient clotting
Positive feed back loop enables:
Factor XI
Factor VIII
Factor V
Thrombin
- to allow for greater fibrin production
- no feedback loop = weak clot

Answer 306

A

Localisation of prothrombin
- dilute clotting factors by blood flow and remove/ break down in liver

Digestion by proteases

Factor Va and VIIIa are degraded by protein C
protein C is activated by thrombin binding to endothelial receptor, thrombomodulin
thrombin acts like a sponge=mop up factors

Specific inhibitors

anti-thrombin iii binds to thrombin, prevents thrombin production
heparin binding increases inhibitor specify to thrombin

Answer 307

A

A - defect in factor VIII reduced thrombin activation
B- deficiency in factor ix, protease that activates factor X

Treatment- recombinant factor VIII counters defected factor

Answer 308

A

Inactive zymogen
Proteolytic activation
Amplification of initial signal by cascade mechanism
Clustering of clotting factors at damage site
Feedback activation by thrombin ensures continued clotting
Termination of clotting by multiple enzymes
Clot breakdown controlled by proteolytic activation

Answer 309

A

Lower activation energy to increase rate at which subserclie is converted into protein

Answer 310

A

Reception rate when enzyme is fully saturated by substrate

- maximum velocity of enzyme

Answer 311

A

Concentration of substrate which permits enzyme to achieve half Vmax
- lower km - higher affinity

Answer 312

A

Competitive - straight line

Non competitive - same as normal curve just lower

Answer 313

A

→ Change rates of chemical reaction

proteases break down proteins
kinases phosphorylate substances
metabolic catalysts

Answer 314

A

Antibodies - bind to and mark foreign antigens
- chains bound together with disulphide bonds
• Constant part = sequence is the same for all antibdies of the same class
• Variable region – unique to antibody help them to target antigens

Answer 315

A

B lymphocytes express antibodies on membrane
Antibodies bind to specific antigen using variable region
Binding is strong - causes change in b lymphocytes so they start multiplying and producing antibodies
more antibodies

Answer 316

A

Receptors bind to and find virus
Bring virus into all
Destroy with lysosomes

Answer 317

A

Macrophages (do phagocytosis)
B lymphocytes
T lymphocyte
- cytotoxic T cells
- helper T cells

Answer 318

A

→ build components that cell can use to build other proteins

- act as reservoirs for amino acid that organism can access when necessary

Answer 319

A

Ferritin. Stores iron

Calmoduin binds calcium and casein (protein of milk)

Answer 320

A

→ carry molecules, allow entry of molecules into the cell

- transports proteins are in the cell membrane and can transfer molecules into the cell

Answer 321

A

Hemoglobin, the iron-containing protein transports oxygen from the lungs to other parts of the body
aquaporins
gated channels - movement of ions
carrier proteins

Answer 322

A

Active transport
Simple diffusion
Passive diffusion

Answer 323

A

> receptors bound to membranes bind to signals then induce a cascade of actions - second messengers
communicate quickly and effectively

Answer 324

A

Receptors built into the membrane of a nerve cell detect signaling molecules released by other nerve cells. Light (eyes) and olfactory receptors (smells)
growth actors - recognise growth factors
tyrosine kinase receptor - bind to growth factor and are phosphorylated, form heterodimer so they can bind to signal transducer protein
gpcr

Answer 325

A

→ coordination of an organisms activities

Answer 326

A

insulin

hormone secreted by the pancreas, causes other tissues to take up glucose, thus regulating blood sugar, concentration

Answer 327

A

→ movement

Can move part of a cell or whole animals

Answer 328

A

Actin and myosin proteins = responsible for muscle contraction

myosin fibres move using ATP = power stroke
myosin heads bring actin filaments towards one another

Answer 329

A

-Support, shape and anchor cells

Answer 330

A

Keratin is the protein of hair, horns, feathers, and other skin appendages.
Collagen and elastin proteins provide a fibrous framework in animal connective tissues.

Answer 331

A

Make up fibres inside cells
provide structure and support
because eukaryotic cells don’t have cell walls

Answer 332

A

Microtubules - tubin polymers
microfilaments - actin filaments
intermediate filaments

Answer 333

A

2 different peptides- alpha and beta

bound to gtp
plus and minus end
microtubules associated proteins
kinesin and dynein proteins - move along micro-tubules and bind to vesicles

Answer 334

A

Globular action- g
Fibre actin- f

Actin bound to gtp arrives at plus end
Hydrolysis to ATP
Actin dissociates at minus end

Answer 335

A

→ used to correct misfolded proteins -refold them

Hsp 70 = chaperonin
- bind to hydrophobic residues on protein, sometimes during protein synthesis to prevent misfolding and degradation

Hsp 60 = chaperonin
-specific structure that polypeptide enters, it is folded correctly in the structure so that it exits the structure as properly folded fully active protein

Answer 336

A

Forms:

amphorous aggregates
oligomer’s
amyloid fibrils

These can be dealt with using autophagy

Answer 337

A

Formed when misfolded ed proteins stick together with other misfolded led proteins
can contribute to Alzheimer’s, Huntington’s and Parkinson,

Answer 338

A

→ misfiled prion proteins responsible for neurodegenerative disorders
- has 3 more helixes and beta cells

scrapie
mad cow disease
chronic wasting disease
- Can be infectious
- If one protein is misfolded this can bind to other proteins of the same kid and transform them to also be misfolded
- This chain keeps going

Answer 339

A

Regulate gene transcription
- Bind to DNA and control what genes are read
- Examples: transcription factors TBP or TFIIB

Answer 340

A

-model of medical practice where care is tailored to specific patient

Answer 341

A

– Treatment options are based on the precise phenotype of that particular patient.
– Biomarkers are used alongside genetic screening.
– surgical approaches, taking into account an individual’s unique anatomy, subtle differences to our anatomy

Answer 342

A

Understand what makes the patients difference – medical, family history, lifestyle, gene mutations, biomarkers
Stratification – using personal info group patients into different sub groups of patients
Now we can think about treatments specific to them
Should give positive effects

Answer 343

A

some patients have

positive effects
adverse effects
no effects

Answer 344

A

Blood donations
- must understand patient blood group and give compatible blood type

Tissue typing
-Matching HLA antigens – ensure body can tolerate and match donor organ

Answer 345

A

Genomics - genes
Transcriptomics - make up of gene
Proteomics - proteins
Epigenomics - gene regulation
Metabolimics - metabolites, how cell functions
Nutrigenomics - food, energy and disease

Answer 346

A

Understand mutation → tumour
- genotyping CYP2D6, which metabolises tamoxifen, mutated CYP2D6 can’t do this

Car -t therapy
- use patient own immune cells to destroy cancer cells

Answer 347

A

Harvest patient T cells
1. Make CAR in the lap
2. Insert CAR gene using a retrovirus vector into the T cell
3. T cell incorporates CAR gene into its genetic code
4. Select T cells that express CAR receptor
5. Expand that T cell population
6. Reintroduce them into patient – find and destory cancer cells to shrink tumour a lot or enough for tumour to be surgically removed

Answer 348

A

Patient put on multiple drug regimens (prevent disease progressing) - not all drugs work due to different causes of arthritis

screen patient to find out what causes their arthritis
refine therapeutic treatment

Answer 349

A

Gut contains microbiome - help digestion and fight infection
-understand patient micribiome makeup
- understand differences in microbiomes between diseases
Can help treatment of gut and gi tract diseases like Ibd

Answer 350

A

Patients can have significant differences in their anatomy

combine info about patient and info from surgical registries
surgical registries. = info on patient type, materials, outcome, impant type

Answer 351

A

probe to be attached to implant and all instuments being used to positon implants, computer and cameras that understand patient measurements

– allow surgeon to implant the implant replacement within 1 degree of accuracy instead of how it is normally done by eye
- Patient metrics taken on surgery day
– best inform how to implant the implant

Answer 352

A

expensive
time consuming
drugs may not be suitable to target disease
Medical community fails to see reasoning behind this method
relies alot on data - but data should be clear and show same outcome
ethics -collecting data from patients
not necessary to apply to all diseases as some diseases do just have one particular causes presentation and so they have one targeted treatment

Answer 353

A

Capacity to perform work
Exist in many inter convertible forms
Can’t be created or destroyed

Answer 354

A

Biosynthesis – producing stuff
- Transport
- Mechanical
- Electrochemical

Answer 355

A

Is the processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body

Answer 356

A

Catabolism
- breaks down molecules to release energy, produce reducing power

Anabolism
- makes large molecules and requires energy, reducing power and raw materials

Answer 357

A

Breaking bonds releases energy

Making bonds uses energy

Answer 358

A

Exergonic - more energy released than used

Endergonic - more energy used than released

Answer 359

A

Metabolism uses energy released from exergonic reactions to supply endergonic reactions

Answer 360

A

• Carbohydrate – mostly supplies energy (monosaccharides)
• Protein – energy and amino acids (deaminate to use for energy)
• Fat - energy and essential fatty acids
• Vitamins & minerals – essential
Essential minerals - sodium, potassium, calcium etc
Essential vitamins - fat and water soluble A.B,K.c- D E
• Water – maintains hydration, essential solvent and coolant
• Fibre – necessary for normal GI function

Answer 361

A

Transport Nutrients on the way to tissues for:
• Utlisation
• Storage
• Inter conversion
And some materials are used by blood
• Proteins, clotting factors
• Waste products from tissues –> excretion

Answer 362

A

Fluctuates

rises after a meal
reduces after exercise

Answer 363

A

Maintains resting activity of body

- maintenance of cells, organs and body temperature

Answer 364

A

• Body size (SA) bigger = higher BMR
• Gener (male BMR is higher than female)
• Environmental temperature
• Factors tending to change body temperature (e.g. fever)
• Endocrine status
– Thyroid = underactive thyroid reduces BMR
– Reproductive hormones

Answer 365

A

- energy required for this depends on intensity and duration of activity
Reflects energy demands of:
– Skeletal muscle 
– Heart muscle 
– Respiratory muscles

Answer 366

A

if energy intake = energy expenditure → stable body weight
• Incease energy expenditure – energy store increase
• If expenditure exceed intake first energy stores will deplete, then other body components (protein) will be utilised to provide energy

Answer 367

A

carbohydrates store energy for immediate use
lipids in adipose tissue store energy for long term use
muscle protein can be converted to carbohydrates

Answer 368

A

Weight (kg) / height (m2)
- doesn't account for muscle bulk
- used for population not individuals
<18.5= underweight
>35 morbidly obese
28.5-24.9=normal

Answer 369

A

Major potentially preventable cause of death
Co morbidity:
-diabetes
- cardiovascular disease
-hypertension
- gall bladder disease

Answer 370

A

Damage from low energy intake
deficiency diseases of other nutrients
low protein intake

Answer 371

A

Arterial end of capillary

high blood pressure
osmotic pressure outside

Venous end of a capillary

low blood pressure
osmotic pressure from outside is higher

Net movement of fluid into blood vessel

Answer 372

A

Some metabollic pathways occur in all cells
- Others are restricted to some cell types
- Some may be further restricted to compartments within cells – e.g. inside mitochondria

Answer 373

A

Break down larger molecules –> smaller one (create intermediary metabolites)
- Release large amounts of free energy to be used by cell
- Oxidative – release Hydrogen atom
- Reducing power

Answer 374

A

Synthesise larger important cellular components – from intermediary metabolites
- Use energy from catabolism ATP
- Reductive – use hydrogen ions from catabolism

Answer 375

A

Digestion
Absorption into blood
Anabolism - use to make endings
Acetal coa breaks substances down to precursors
recycle precursor
oxidise precursor
creates reducing power
use reducing power in anabolism
Waste =co2, water used ‘

Answer 376

A

building block materials
dynamic state of components = turnover
cell growth, division, repair
organic precursors acetyl coa
biosyntnetic reducing power NADH NADPH
energy

Answer 377

A

Capacity to do work

biosynthetic - anabolism
transport - transport ions
mechanical - muscle contraction
electrical-action potential
osmotic -kidney

Answer 378

A

• Exergonic – release energy, delta g< 0 , spontaneous reaction
• Endergonic – require energy, delat g > 0, reaction is not spontaneous
Gibbs free energy - useful energy

Answer 379

A

Removal of electrons or protons
Or
Addition of oxygen

Answer 380

A

Gaining of electrons or protons
Or
Losing oxygen

Answer 381

A

→ transfer electrons and proteins
• Total conc o f oxidised and reduced carriers is constant – cycle between both processes
Act as carriers for reducing power – used for:
• ATP production (NAD+)
• Biosynthesis anabolism (NADPH)

Answer 382

A

NAD+ → NADH
NADP+ → NADPH + H+
FAD → FADH2

Answer 383

A

Via oxidation - exergonic

* Directly – using NADPH in biosynthesis (make larger compounds)
* Indirectly – using NADH as a carrier in mitochondrial system

Answer 384

A

ATP –> ADP = breaks ‘ a high energy phosphate bond which releases a lot of energy (31kj mole)
ADP–>ATP = put in 31KJ mole of energy to reform the high energy bond

used as a carrier not storage
constant turnover
ATP is stable in absence of catalysts - control energy

Answer 385

A

High ATP concentrations – favour anabolic pathways = activated
Low ATP concentrations – high ADP, high AMP, catabolic pathways are activated as cells need to make more ATP

Adenylate kinase – 2ADP –> ATP + AMP
• AMP acts as low energy signal – feedback system high AMP suggest low energy so catabolic pathways are activated = more ATP

Answer 386

A

—> activate anabolic pathways
• High ATP, NADH, NADPH, FAD2H
• Signal that energy is high – can make large molecules

Answer 387

A

—> activate catabolic pathways
• High ADP, AMP, NAD+, NADP+, FAD
• Signal that energy is low – make more energy

Answer 388

A

—> store energy when supply exceeds demand

• Stores = polymer macromolecules or fuel molecules – glycogen, triglyceride

Answer 389

A

converts creatine –> creatine phosphate/ phosphocreatine
Move phosphate group onto creatine
• Reversible reaction
High ATP = form creatine phosphate
Low ATP – form creatine and ATP (short term boost)

Answer 390

A

Creatine + ATP ——-> creatine phosphate + ADP

Answer 391

A

Marker for muscle damage - when muscle bursts it releases ck - measure levelels
• Myocardial infarction –region of the cardiac muscle is deprived of blood, cells die and burst = increased CK in blood, analyse CK to determine if it has come from cardiac or skeletal muscle

Answer 392

A

Oxygen storage protein

in skeletal + cardiac muscle
high affinity for oxygen- slow release
supplies oxygen when oxygencevels are critically low = haemoglobin can’t supply enough

Answer 393

A

Oxygen transport protein

in blood
transports oxygen from lungs → tissues
low affinity to oxygen at tissues -release

Answer 394

A

protoporphyrin ring and an iron (Fe) atom bound to 4 nitrogen atoms

iron atom is bound to histidine residue on protein
iron from can form 2 bonds to one molecule of oxygen

Answer 395

A

Monomer, one subunit of 153aa
• 75% α-helical
• His 93 covalently linked to Fe (proximal histidine)

Oxygen is more hidden in structure = slower release

Answer 396

A

Iron (as it is bound to histidine) sits slightly below the plane of the ring

Answer 397

A

The oxygen bound to iron pulls up iron so it sis’s in the same plane as everything else
binding of one oxygen can lead to cooperative binding

Answer 398

A

→ hyperbolic dependence on oxygen

low oxygen pp = high affinity
myoglobin is fully saturated at a lower oxygen pp

Answer 399

A

Each haemoglobin has 4 subunits 2 alpha and 2 beta
- Each subunit carries 2 oxygen atoms so can carry 8 in total
- Each chain contains an essential haem prosthetic group

Answer 400

A

Exist in 2 states

T (tense) state = low affinity to oxygen
R (relaxed) state = high affinity to oxygen

Answer 401

A

Conformational change where oxygen binding promotes stabilization of R state

Answer 402

A

Binding affinity for oxygen increases as more oxygen molecules bind to Hb subunits
1. Binding of 1st O2 molecule to 1 subunit is hard – low affinity (high pp)
2. Binding of last O2 molecule to 4th subunit is very easy – high affinity
3. Due to confirmation changes to Hb
4. Conformational changes – changes shape pull subunits making them more relaxed

Answer 403

A

increased carbon dioxide which reduces haemoglobin affinity to oxygen
- Greater the CO2 = greater the change in pH (acidity)
CO2 causes low pp of oxygen as it represent oxygen used up for respiration = low affinity

release of O2 occurs where CO2 concentration is high

Answer 404

A

2,3 bisphosphoglycerate – accumulates in RBCs, product of glycolysis
- without 2,3 BPG affinity of haemoglobin
is similar to affinity of myoglobin
- so haemoglobin behaves like myoglobin = bad

Answer 405

A

contains no 2,3-BPG and so it acts more like myoglobin

- has greater affinity for oxygenat low partial pressures than mother

Answer 406

A

Maintains t state in haemoglobin
Binds in centre of tetramer
conformational change causes T state stabilisation
reduce access to haem groups for oxygen to bind to

Doesn’t stop oxygen binding just reduces oxygen affinity
- oxygen can readily dissociate at low tissue conc

Answer 407

A

2,3BGP concentration increases, promoting oxygen release

- athletes train at high altitudes to train body into releasing more oxygen

Answer 408

A

H+ and CO2 binding to haemoglobin → lowers haemoglobin affinity to oxygen

High co2 and h+ = lower oxygen affinity (released)
low co2 and h+ = higher oxygen affinity (bound)

Answer 409

A

Low pH = low affinity (higher metabolically active cells)

* High pH = high affinity

Answer 410

A

• CO binds to haemoglobin 250x more readily than O2 - reduces ability of oxygen to bind

Fatal – CO combines with ferromyglovin and ferrohaemoglobin and blocks oxygen transport

Answer 411

A

hyperbaric O2 (3x atmospheric pressure) reduces the half-life of CO-hb (carbon monoxide in blood) to ~23 minutes (1/3 of normal half-life) 
- breathe pure oxygen at higher pressure

Hyperbaric treatment also allows direct diffusion of O2 to tissues, bypassing the normal circulation –
• Causes oxygen at very high pressures to dissociate into tissues

Answer 412

A

2 subtypes -alpha2 and beta 2

90% of hb

Answer 413

A

Higher binding affinity for O2 than HbA which allows transfer of O2 to foetal blood supply from the mother
- No 2,3-BPG so curve sits to the left

Answer 414

A

Measure for diabetes control
• Glycosylation of HbA – HbA1c = more HbA1c the higher the blood glucose, can tell you about long term diabetes management

Answer 415

A

genetic disorders where there is an imbalance between the number of alpha and beta globin chains

Answer 416

A

Decreased or absent β-globin chain production
- Only α-chains present but they are unable to form stable tetramers – can’t regulate oxygen dissociation, reduced ability to carry oxygen

Answer 417

A

decreased or absent α-globin chain production,
- So only β-globin chain production – but can form a stable tetramer with a greater affinity for oxygen but a problem dissociating oxygen

Answer 418

A

activators - shift curve left and enhance high affinity R state
inhibitors - shift curve right and enhance low affinity t state

Answer 419

A

Increased affinity = better loader - shift left

Decreased affinity = better released - shift right

Answer 420

A

One protein has many different functions that are mediated by different domains with different structures and functions

Answer 421

A

Proteins are targeted to different compartments of the cell
- Proteins have different and multiple functions – cell must organise these and regulate which proteins are active

Answer 422

A

-> control time and place where the protein functions

Answer 423

A

→ localisation sequences
Specific amino acid sequences code signals to direct proteins to specific regions

→ post translational modification
Signal transduction pathway receptors signal for modifications of proteins within the cell

→ binding to scaffolding proteins
specific proteins with no enzymatic activity, but allow other proteins to bind and join together -relay signals and induce separate pathways

Answer 424

A

Lysosomal proteases that are only active at ph 5.5

1. At normal pH active centre of protein is blocked has 2 aspartic acids 
2. At high pH (normal) they are deprotonated – so N terminal binds to active centre of protien = inactive
3. If pH changes (e.g. addition of a lysosome) = protonation of aspartic acids, release N terminal and free up centre of protein --> activation

Answer 425

A

Toxin has 2 domains A catalytic and B regulatory

1. B domain binds to the human receptor 
2. Endocytosis – brings protein into cell
3. Vesicel combines/ fuse with lysosome = pH chanage 
4. Low pH breaks disulphide bond between A and B domains
5. T domain changes conformation, inside goes outside, so hydrophobic amino acids move to the outside of protein and bind to vesicle membrane 
6. A domain is released into cytoplasm using T as a channel
7. A domain binds to EF-2 and blocks translation
8. Fatal for cells

Answer 426

A

Active when bound to protein
once hydrolysed - inactive
Once released = inactive
3 phosphate groups

Answer 427

A

Protein that bind to gtp
-active-induces signalling transduction pathway

* GTP bound = active
* GTP hydrolysed to GDP = inactive 
* GTP released = inactive

Answer 428

A

Rho bound to GDP and an inhibitor (GDI) = inactive
Inhibitor is released, Rho still bound to GDP is still inactive
GEF helps Rho to be activated by binding the protein from GDP –> to GTP = active
Effect many other proteins
GAP inactivates protein by transforming GTP

GEF = activated protein binds to GDP - promotes dissociation of GDP from the gtpase
GAP = inactivates protein by hydrolysing GTP bound form to inactive GDP bound form

Answer 429

A

GEP
- gtp binds to gtpase = active = signal transduction pathway promoted

GAP
- gtp hydrolysed to GDP = inactive = signal transduction pathway inhibited

Answer 430

A

GPCR transmembrane receptors activated by signalling molecules
- When activated there is a change in the protein
- Protein bind to GPCR
- Release GDP bind to GTP
- Affect other proteins (g protein -cause dissociation of alpha subunit )
- Signalling cascade

Answer 431

A

Works in elongation during translation, carries tRNA to ribosome
but can only bind to and carry tRNA when bound to gtp
tRNA is released when gtp hydrolysed to GDP

Answer 432

A

→ move motor protein (myosin and actin fibres) pushing myosin head along actin

1. ATP binds to ATP binding site on protein 
2. Conformational change in protein
3. Hydrolysis of ATP
4. Conformational change 
5. Release ATP 
6. Protein returns to original state

Answer 433

A

→ controls movement of molecules in t out of cell
Molecule binds to receptor

* Binding of ATP = conformational change 
* Protein opens up and releases molecules (push molecule out of cell)
* ATP hydrolysis – protein returns to normal conformation

Answer 434

A

PKA phosphorylates regulatory domain and opens it up so allows ATP to bind to secondary domains
Opens up channels so ions can move through

WITH CF – mutation in receptor = malfunctioning channel ende can’t open so no moveoment of ions out of cell, water moves out of cell → thick mucus

WITH CHOLERA = toxin removes phosphorylation via of PKA

Answer 435

A

bind with 3 sodium from cytoplasm
1. With ATP = phosphorylates transporter
2. Change in conformation
3. Sodium molecules released
4. Potasssium molecules bind
  - dephosphorylation - change in conformation
5. Potassium moves into cell

Answer 436

A

Protein kinases
- add phosphate group to protein (amino acids - serine, threonine tyrosine)

Protein phosphatases
- remove the phosphate group from proteins

Answer 437

A

When inactive SH2 is normally bound to phosphorylated amino acid = keeping it inactive
1. Removal of phosphate – opens up protein loosens structires
2. SH3 binds to specific ligands
3. Kinase can now phosphorylate tyrosine itself and self active
4. Active kinase can phosphorylayte other things

Answer 438

A

→ activate by binding with amp and phosphate - using protein kinase A

1. Binding of AMP (when cells are running out of ATP) - activates enzyme to work with glycogen
2. Phosphorylation via phosphorylase kinase phosphorylates the enzyme and activates it

Answer 439

A

4 subunits:
- 2 regulatory (r)
- 2 catalytic (C)
When bound together -inactive

→ activated by binding to cAMP causes regulatory and catalytic to dissociate
- catalytic subunits - phosphorylate things

Answer 440

A

-controlling protein degradation controls the amount of protein

Proteasome – protein complex with many proteolytic residues

Answer 441

A

Labelling proteins for degradation by binding to lysine in protein

Monoubiquitylation - add 1 ubiquitin - hormone regulation
Multiubiquityation - few molecules of ubiquitin bind to proteins -endocytosis
polyubiquitylation - multiple molecules of ubiquitin one after the other
- add to lysine 63= Dna repair
- add to lysine 43 - proteasom degradation

Answer 442

A

post-translational covalent addition of sugar molecules (oligosaccharides) to asparagine, serine or threonine residues on a protein molecule. Glycosylation can add a single sugar or a chain of sugars at any given site.

Answer 443

A

Add lipid acids to protein → direct proteins to membranes

Answer 444

A

Repair = viable ell
no repair = cell death
mis repair = repair causing mutation leading to cancer or cell dean

Answer 445

A

Accumulation of mutations

Answer 446

A

Takes advantage of double stranded nature of DNA molecule

- if one strand is damaged duplicate the other strand to be used as repair

Answer 447

A

Mismatch repair

Base excision repair

Nucleotide excision repair

Answer 448

A

Polymerase may mis incorporate nucleotide
- proofreading function = repair most mistakes not all
So you can still end up with a base mismatch

Answer 449

A

Damage recognised by specific damage recognition proteins
1. Decide which strand is correct one and which has error (normally done by MutL protein) - determining strand specificity
2. Use exonucleases to cut out damaged DNA
3. Use DNA and undamaged strand as template to make new DNA with polymerase and ligase

Answer 450

A

Differ in ability to recognise specific type s of DNA structure

insertion loops
deletion loops
mismatches
single base loops

Answer 451

A

Early age of onset
very nigh propability that mutation will develop
autosomal dominance = high penetrance
microsatellite instability and accumulation of mutation
Repeated microsatellite sequences

Tumour cells have almost normal karyotype

Answer 452

A

Synthesising one/ a few nucleotides

Base is chopped
Backbone is opened
Polymerase incorporate a single/few nucleotides using other strand as a template

Answer 453

A

Similar damage, damage to a single base

Damage recognised by DNA glycosylase - removes base and opens up back bone
Assemble DNA with nucleotides and polymerase
Remove old strand
ligase seals backbone

Answer 454

A

Depend on:

Nature of damage
nature of glycosylase
nature of DNA polymerase

Answer 455

A

Removal of incorrect organic base by appropriate DNA N-glycosylase to create an AP site
1. AP endonuclease nicks on the 5’ side of the AP site to generate a 3’ OH terminus
  Extension of the 3’-OH terminus by a DNA polymerase (fill the gap)

Answer 456

A

Many types

A specifically damaged base is recognised by specific glycosylase
Eukaryotic glycosylase. Have N terminal additions that specify location and protein interaction

Answer 457

A

Removes base but leaves backbone intact

- AP endonuclease is required to break backbone

Answer 458

A

Enzyme removes base and opens/ modifies back bone

- Easier for AP endonuclease to work

Answer 459

A

DNA polymerase b pathway - short patch repair

complex of DNA ligase and protein
DNA polymerase incorporates nucleotide and lipase reseals backbone

Answer 460

A

Cancers have mutations in ber genes

Demethylation of specific genes dependent on ber

Answer 461

A

Damage recognition
1. Binding of a multi protein complex at the damaged site -recognised by mis shaped DNA
2. Double incision of the damaged strand several nucleotides away from the damaged site, on both the 5’ and 3’ sides - transcription factor opens and unwind DNA
3. Removal of the damage containing oligonucleotide from between the two nicks -using exonuclease
4. Filling in of the resulting gap by a DNA polymerase
5. Ligation

Answer 462

A

Extremely flexible

- corrects damage that distorts and alters chemistry of DNA

Answer 463

A

Global excision repair

Transcription coupled repair

Happens after transcription
DNA repair ensures correct gene transcription

Answer 464

A

Xeroderma pigmentosum

Cockayne’s syndrome

Trichotniodystrophy

Answer 465

A

Severe light sensitivity and pigmentation irregularities

frequent neurological defects
early onset of skin cancer and elevated frequency of other cancer

Answer 466

A

Dwarfism, facial and limb abnormalities

neurological abnormalities
early death
sometimes light sensitivity

Answer 467

A

Sulfur's deficient hair brittle
Facial abnormalities
Short stature
Ichthyosis - fish like scales
Light sensitivity

Answer 468

A

Very distinct phenotypes but still deal with the same gene
strains with same phenotype but mutation found in different genes
2 mutants can = one normal

Answer 469

A

Occurs it replication coupled DNA repair goes wrong

higher frequency’s of sister chromatid exchanges
chromosomal instability
immune defects
autosomal recessive
pigmented areas

Answer 470

A

Essential for survival,
pathways dependent on homologous recombinations
non homologous end joining

Answer 471

A

DNA damage that can cause a double stranded break

simple double stranded break - easy to connect
complicated double stranded break

Answer 472

A

Can only occur in damaged cells that nave passed the s phase

- they have 2 chromosomes - one can be used as a template

Answer 473

A

They don’t cause cancer
But people with a faulty copy of these genes have a higher than average risk of developing cancers like breast and prostate

Answer 474

A

Break = signaling cascade
1. Complex of proteins brings the ends together
2. Complex of ligase ligates both backbones

Answer 475

A

Inaccurate

* Nucleotides chopped away
* Nucleotides are added
* Issue is that it is done very quickly 
* Break in the DNA in coding DNA = bad, breka in DNA no continuation of mitosis don't pass cell cycle checkpoint

Answer 476

A

Catalyse formation of covalent bond between juxtapose 5’ phosphate and 3’ oh groups in DNA backbone
- Blunt and sticky ends are ligated

Answer 477

A

-Isolation
- analysing
- manipulating
Individual genes, gene sets and whole genomes

Answer 478

A

Selectively cleaving DNA
Ligating gene sequence into original DNA
new sequence is incorporated within cells via recombinant plasmid
new colony of cells formed containing altered DNA with target gene

Answer 479

A

Preparation of very pure DNA samples
1. Cutting and splicing DNA molecules
2. Analysis of DNA size
3. Getting the DNA into host cells
4. ID of host cells that contain recombinant DNA

Answer 480

A

protect DNA against damaging enzymes
- deactivate enzymes by heat or removal of divalent cations using chelating agents
Storage of DNA in ethanol at low temperatures to prevent water free radicals attacking DNA

Answer 481

A

Blood (must remain unclotted in EDTA tubes)
amniocytes (from amniocentesis fluid)
tissue biopsies
cultured cells
paraffin embedded tissue cells

Answer 482

A

Cell collection – have enough cells to get enough DNA
1. Cell lysis – break cells
2. Removal of cellular proteins – using proteolytic digestion (proteases)
3. Precipitation and washing with alcohol (ethanol)

Answer 483

A

→ Must get enough cells for success

Gently chewing the inside of the mouth combined with a water mouth wash is used to dislodge epithelial cells lining the mouth

Answer 484

A

→ breaking down cell - disrupt lipid bilayer so DNA can escape

-lysis buffer to maintain pH of solution at a level where DNA is stable (7/8) and contains EDTA to protect against endo/exonuclease activity

Use SDS a protein solution – most common one is 1% SDS to break open the cell and nuclear membranes, allowing the DNA to be released into the solution
SDS also denatures and unfolds proteins, making them more susceptible to proteolytic cleavage)

Answer 485

A

→ Biological powders contain proteases to destroy nuclear proteins that bind DNA and cytoplasmic enzymes that breakdown and destroy DNA.
- Then extract the proteins using orgaic solvent (phenol-chloroform-isoamyl alcohol)

• Protease treatment increases the amount of intact DNA that is extracted.

Answer 486

A

DNA is not soluble in ethanol but proteins are

Answer 487

A

Most are from bacteria → original function to cleave bacteriophage DNA

bacterial DNA is methylated
external DNA is not methylated = methylated
DNA is not cleaved

Answer 488

A

→ use restriction enzymes to cleave DNA and expose sticky ends

modify DNA ends

Answer 489

A

• Alkaline Phosphatases – remove 5’ phosphate groups = hydroxyl is left, ligase can’t ligate
This prevents the rejoining of cut ends and self-ligation

* Terminal transferases – transfer nucleotides to the 3’ end of a DNA molecule – useful w blunt ends to change them to sticky ends 
* Nucleotide kinases – transfer single phosphate group from ATP to the 5’ end of DNA

Answer 490

A

Use PCR

1. Purify DNA as describe above
2. Design primers
3. Use PCR
4. Amplify fragment

Answer 491

A

Break membrane of host cells with heat shock or electroporation= so recombinant DNA can enter cell through pores
Transfer recombinant DNA to cells by direct microinjection to target cells

Or

Viral transfection = vector using viral DNA, viral vector binds to outside of cell and then injects cell with the recombinant plasmid

Answer 492

A

vehicle used to transfer genetic material to target cell
DNA molecule capable of independent replication in host
capable of carrying foreign DNA

Answer 493

A

Contains marker or marker gene to observe alls containing recombinant DNA = selection marker
origin of replication = specific sequenced recognised as where replication starts
amplify plasmid - plating and bacteria duplication

Answer 494

A

Isolate and amplify DNA and express foreign DNA in host cell

- allows on demand expression of protein for studying, generating antigens or vaccine development

Answer 495

A

Containing everything a cloning vector has plus:

promoter region
Ribosome binding site
polyadenylation site
2 selection markers
Termination

Answer 496

A

Induction – promotor is inactive until inducer bind to promoter sequence = produce mRNA
Repression – promoter is active and produces mRNA until it binds to a repressor (repressor tends to be protein formed as a result of the mRNA produced)

→ determines rate at which mRNA is synthesised and how much protein is expressed

Answer 497

A

Transfection and transformation

→ all methods create situation where membrane is open-for short period of time due to recombinant DNA

* Electroporation = Blast cells with electric current, opens up pores in the membranes
* Chemicals
* Lipid delivery
* Microinjection
* Viral delivery

Answer 498

A

Put target recombinant DNA that you have created into a mini vesicle made of a lipid membrane like structure
1. Endocytosis – structure is taken inside the cells
2. Structure releases the DNA

Answer 499

A

High jack the viruses as they are good at getting into the cell
- Create virus carrying the recombinant DNA inside
- DNA is delivered into cells

Answer 500

A

• Use GFP – green fluorescent protein
• Clone the pGLO plasmid which contain GFP and bla
Bla gene = this gene gets the protein to grown in the presence of ampicilin
GFP gene = bacteria with this gene glow under or near UV light
• These are attathced to protein of interest

Answer 501

A

To find mutations in the diagnosis of genetic diseases - to detect a change in the sequence of a gene

Answer 502

A

Determines exact position of mutation within a gene

- determines type of mutation

Answer 503

A

Chemical degradation = degradation of DNA, exonuclease approach
- Chain termination = sequencing newly synthesized DNA strand and terminating it in different places - modern methods

Answer 504

A

DNA polymerase reads and synthesises a new complimentary strand barring a primer and deoxynucleotides present - mix of shorter fragments that all end with T corresponding to A in original strand
dttp
auto-radiography - radioactive dTTP or fluorescently labelled ddNTP can be used to determine the sequence of fragments that are synthesised

Answer 505

A

5 % of the deoxyTTP (dTTP) nucleotides are replaced by dideoxyTTP (ddTTP), which lacks a hydroxyl group

= this causes each strand to terminate randomly when a ddTTP is incorporated at the growing 3’ end of the strand

block replication of DNA by polymerase
Used for mapping

Answer 506

A

Incorporated radioactive ddTTP is detected by using X ray film (autoradiography)

* Radioactive T at the end of each fragment
* Run the whole mix of fragments on the gel
* Longest fragment at the top near the negative end
* Shortest fragment at the bottom near the positive end 
* Read gel from bottom to top (as it separates fragments by size) you get a sequence of DNA from 5' to 3'

Answer 507

A

→ Fluorescently labelled ddNTP assigns a chlorophyll to each of the 4 bases - colours appear on fluorescent sequencing gel

The use of fluorescently-labelled ddNTP terminators has allowed automation and high-throughput sequencing.

This technical advance was essential for the rapid completion of the Human Genome Project.
A different fluorescent labelling molecule (“fluorophore”) is used for each of the ddNTPs, each with a different emission colour.
All four sequencing reactions can be carried out simultaneously in a single tube, and all four are loaded into a single well of the PAGE gel electrophoresis separates the coloured bands.• time a fragment takes to reach the detector is a direct measure of its size (the smallest ones arrive the most quickly) largest arrive later

Answer 508

A

to identify the approximate 100,000 (as believed at that time) genes in the human DNA.
- determine the sequences of the 3 billion bases that make up human DNA.
- store this information in databases.
- develop tools for data analysis.
- address the ethical, legal, and social issues that arise from genome research.

Answer 509

A

→ sequence large stretches of DNA with shotgun sequences

1. Prepare pure DNA – total human DNA cleaved by specific restriction enzyme
2. Clone it, DNA clone – use BAC factors as it can add longer lengths of DNA to itself
3. Approx 20000 bac clones = genome
4. Bacs are sequenced , they can be mapped to previously sequenced known parts of the genome (used as markers)
5. All sequences are assembled in a similar simplified way chain termination method  = give sequence of the whole chromosome by looking at overlapping sequences find the sequence within the sequence, find the DNA fragment within the DNA sequence, localize it to assemble Overlapping ends into a continuous sequence

Answer 510

A

Bac library = collection of bac clones containing entire human genome

* BAC clones were ‘mapped’ (order and approx. chromosomal location determined), using microsatellite markers and sequence tagged sites (STSs)
* Known position of repetitive sequences in human genome = practical use in mapping of genome

Answer 511

A

Better understanding of genetic variance in diseases and human genotypes
pre screening for diseases
storage of genome data in a database for future reference by hospitals

Answer 512

A

Map the Rare functional variants (Mendelian diseases)
- Pharmacogenetic variants (150 gene-drug pairs in the FDA “Table of Pharmacogenomic Biomarkers in Drug Labels”, but only 40 genes involved) = see which variants of the genes determine the response to drugs
- Oncogenomic – study of cancer associate genes

Answer 513

A

• Neonatal sequencing
• Maternal blood sequencing
• Direct To Consumer (DTC) genomics brought to doctors
DTC based on the simple technical advance that we can sequence long sequences very easily, - USB contain genome data

Answer 514

A

• Single nucleotide variants 
	• Multi-nucleotide variants 
	Small insertions/deletions (indels) 
	Large copy number variants (CNVs) 
	Inversions 
	Translocations 
	Aneuploidy

Answer 515

A

Fairness in the use of genetic info (how and who can use it)
- Privacy and confidentiality
- Psychological impact and stigmatization – knowing that you have a mutation
- Genetic testing
- Reproductive issues
- education, standards, and quality control.
- commercialization.
- conceptual and philosophical implications.

Answer 516

A

→ induce incorporation of a viral vector carrying healthy gene for the disease

inject vector into cells with mutated genes
healthy gene vector is incorporated with original genes
healthy gene creates functional protein = normall cell

Answer 517

A

In some cases gene vectors can introduce cancer or some other lethal virus

Answer 518

A

Cf is ideal for gene therapy because:

1. it is a single gene defect, don't have to correct many or multiple genes
2. It is a recessive condition, with heterozygotes being phenotypically normal (suggesting gene dosage effects are not critical) - can retain one copy of mutated gene in cells 
3. The main pathology is in the lung, which is accessible for treatment; 
4. It is a progressive disease with a virtually normal phenotype at birth, offering a therapeutic window (develop in the teens)

Answer 519

A

the intake of digestion enzymes, nutritional supplements,
- percussion and postural drainage of the lungs, improved antibiotics
- inhalation of aerosols containing medication. = improve lung conditions

Answer 520

A

→ selective insertion I deletion/editing of genes to produce different genotypes

Combine:

* DNA double strand break REPAIR machinery in mammalian cells – non homologous end joining and non homolgous recombination 
* DNA double strand break INDUCTION machinery from bugs

Answer 521

A

When bacteria detects presence of virus DNA it produces two types of short RNA
1. One of the RNA strands contains a sequence that matches the invading virus
2. Two RNAs form complex with kasnine protein (nuclease)
3. When matching sequence (guide RNA) finds its target in the viral genome = kasnine cuts target DNA disabling virus
  Research found that this can be done to cut other DNA by changing guide RNA and cut DNA, cell tries to repair cut but the process s error prone – allows researchers to understand function
  • For more precise mutations researchers can add another piece of DNA with desire sequence that can bind up with cut ends and repair it

Either knock out genes (deletion) or replace gene

Answer 522

A

Should people be allowed to make genetically perfect off spring

Chinese biophysicist He Jiankui’s attempt to use CRISPR technology to modify human embryos and make them resistant to HIV, which led to the birth of twins Lulu and Nana.

Answer 523

A

• Don’t store much carbs but we each a lot of it
• Lipids = efficient storage molecules
Proteins = make up muscles but we don’t really store it

Answer 524

A

• Break down larger molecules into smaller ones (intermediary metabolites)
• Release large amounts of free energy
– Oxidative – release H atoms – ‘ reducing power’
• Release energy

Mainly things like amino acids, glucose, fattyacids,and alcohol can be catabolised = acetyal coa

Answer 525

A

• Synthesise larger important cellular components from intermediary metabolites
• Use energy released from catabolism (ATP)
– Reductive (i.e. use H released in catabolism
• Need energy

Answer 526

A

Stage 1
• breakdown to building block molecules

Stage 2
• breakdown to metabolic intermediates
• Release of ‘reducing power’ and ‘energy’
glycolysis - tiny amounts

Stage 3 - kerb cycle/ tca
• Tricarboxylic acid (Kreb’s) cycle:
• release of ‘reducing power’ and ‘energy’
Input: 2 acetyl coA, 6NAD+, 2FAD, 2ADP, 2 phosphate
Output: 4CO2, 6NADH, 2FAD2H, 2ATP
Provides reducing power and energy for oxidative phosphorylation

Stage 4 - Oxidative phosphorylation:
• conversion of ‘reducing power’ into energy currency, ATP efficient
Input: 10NADH, 2FAD2H, 6O2
Output: ATP (26-28 per glucose) 6H2O, NAD+, FAD

Answer 527

A

Convert to molecules that can be takenup by cells

protein - amino acids
lipids - glycerol and fatty acids
Carbonyarates - monosaccharides
alcohol - almond

Occurs extracellularly in gi tract - molecules absorbed into circulation
- no energy produced

Answer 528

A

Simple molecules → simpler intermediates

Amino acids → ammonium  (later urea), Keto acids, pyruvate, acetyl coa 
Monosaccharides → pyruvate
Fatty acids → acetyl cOA
Glycerol → pyruvate
Alcohol → acetyl coa

Occurs Intracellular (cytosolic & mitochondrial)
• Many pathways (not all in all tissues) - not in RBC
• Oxidative (require coenzymes which are then reduced, e.g. NAD+ → NADH) continous supply of NADH
- includes glycolysis in stage 2
- Some energy (as ATP) produced

Answer 529

A

Occurs in mitochondria

Oxidative (requires NAD+ , FAD)
Some energy (as ATP) produced directly - 32 ATP for every glucose
Acetyl (CH3CO- )converted to 2CO2 – waste product
(Also produces precursors for biosynthesis) - useful compounds for anabolism

Answer 530

A

Occurs in mitochondria

involves Electron transport and ATP synthesis
NADH & FAD2H reoxidised - donate electrons to etc
O2 required (reduced to H2O by taking election ) without it = death
Large amounts of energy (ATP) produced

Answer 531

A

General formula - (CH2O)n n- length of carbon chain

consist of oxygen and carbon
contain either aldehyde (-Cho) aldose or keto groups (c=0) ketose

Answer 532

A

→ Simple sugar units 3-9 carbons

aldose = containing aldehyde (glucose, ribose, galactose)
or Ketose groups = containing ketone (fructose)

Answer 533

A

Exist as ring structures

Carbonyl group reacts with alcohol group = ring
Polar – attracts water a lot of hydrogens - water soluble
Need a carrier to cross membranes
Partially oxidised

Alpha rings = have the oh group on opposite side of ch2oh group
beta rings = have oh group on same side as ch2oh group

Answer 534

A

Diasachharides → 2 monosaccharides (lactose, maltose, sucrose)

Ogliosaccharides → 3-12 monosaccharides (dextrins)

Polysaccharides → 10-100 monosaccharides (glycogen, all polymers of glucose)

Answer 535

A

Disaccharides formed by condensation of 2 monosaccharides
• O-glycosidic bond
• H2O eliminated

Answer 536

A

→ Storage molecule in body: stored in liver and skeletal muscle

Glycogen granules liver and skeletal muscle
- Highly branched
- Alpha 1- 4 straight
- Alpha 1 – 6 bond branch
- Complex branched molecule = good for storage water can’t get in

Answer 537

A

Polymer of glucose
– Major store of glucose in mammals (liver, skeletal muscle)
– a1-4 and a1-6 glycosidic bonds (Highly branched)
– Highly branched = prevent water binding and allows quick breakdown of glycogen

Answer 538

A

Polymer of glucose found in plants
– Mixture of amylose (a1-4 bonds) amd amylopectin and a1-4 and a1-6 glycosidic bonds (Less branched than glycogen)
– GI tract enzymes (amylose) release glucose and maltose
-

Answer 539

A

Structural polymer of glucose in plants
– β1-4 linkages
– No GI enzymes to digest (dietary fibre adds peristalsis important for GI function)
• In animals that can digest cellulose they use bacteria to do this not enzymes

Answer 540

A

-> eat alot of carbs only store a little

Main dietary sources 
	• Starches- glucose 
	• Glycogen- glucose 
	• Sucrose - glucose + fructose 
	• Lactose - glucose + galactose

Answer 541

A

Hydrolysis of glycosidic bonds into glucose galactose fructose – using enzymes:

Saliva = amylase – starch, glycogen —> dextrins
Pancreas = amylase – major enzyme breaks sown dextrins —> monosaccharides

Small intestine = contains enzymes that breakdown carbs
–> diassacharidases on border membrane of epithelial cells breakdown disaccharides
• lactase (lactose) – N.B. lactose intolerance
• Sucrase (Sucrose)
• Pancreatic amylase (a1-4 bonds)
• isomaltase (a1-6 bonds)

Answer 542

A

no lactases to breakdown lactose, lactose isn’t broken down in small intesine, goes to colon, draws water into colon = bloating

Answer 543

A

→ active transport system into epithelial cells then via blood supply to target tissues

– uptake into cells facilitated diffusoion using transport proteins:
• GLUT1- GLUT5
• GLUTs have different distribution and affinities
• can be hormonally controlled (e.g. insulin/GLUT4) - insulin increase number of GLUT4 and activity – take glucose into cells and reduce blood glucose )

Answer 544

A

Blood from small intestine goes to liver via hepatic portal vein-liver breaks down small molecules

whatever we digest and absorb goes through liver
because they are broken down and sent to the liver

Answer 545

A

Blood [glucose] regulated (~5 mM) because some tissues (rbc, wbc, kidney medulla, lens of the eye) have an absolute requirement & uptake by these tissues depends on [blood] (approx. 40g/24 hours)
==== 5 millimolar is normal blood glucose level
• CNS (brain) prefers glucose (approx. 140g/24 hours)
• Some tissues need it for specialised functions (liver, adipose)
• Too high = hyperglaecemia = diabetes
• Too low = hypoglaecemia = low glucose in blood
Dizzy, confused, coma, die

Answer 546

A

Catabolism of glucose - stage 2
→ central pathway of glucose metabolism occurs in all tissues (cystolic)
- intracellular

Overall outcome glucose → pyruvate
Can occur without oxygen with the addition of an enzyme

Answer 547

A

Oxidise glucose / NADH production (reducing power – NADH can donate electrons)
1. Synthesis of ATP from ADP – 2 ATP formed
2. Produces C6 and C3 intermediates (C6 splits into 2 C3 molecules) - no loss of CO2

Answer 548

A

Exergonic, (energy releasing) oxidative
- C6 → 2C3 (No loss of CO2 )
- With one additional enzyme glycolysis is the only pathway that can operate anaerobically (No O2)

Answer 549

A

Step 1 (hexokinase) - phosphorylation of glucose by hexokinase

Step 3 (phosphofructokinase 1 ) - it is key controlling step of glycolysis

Step 10 (pyruvate kinase) - one direction step can be reversed back to previous step

Answer 550

A

Steps 1-3

Step 1 - glucose is converted to glucose 6 phosphate (G6P)

Step 2- isomerisation of glucose 6 phosphate to fructose 6 phosphate.

Step 3 - committing step of glycolysis

Step 1 and 3 both have large negative free energy values (delta g) and are therefore irreversible

Answer 551

A

→ Glucose is converted to glucose 6 phosphate via phosphorylation (more reactive)
• ATP need for phosphorylation
• Polar phosphate group addition = Makes glucose negatively charged (anionic) =Charge prevents passage back across the plasma membrane

Answer 552

A

Isomerisation of glucose 6 phosphate to fructose 6 phosphate

done by phosphoglucoisomerase
reversible

Answer 553

A

Committing step: first step that commits glucose to metabolism via glycolysis – glucose 6 phosphate in step 3 is committed to go through glycolysis

further phosphorylation - making glucose even more reactive

Answer 554

A

Reactions/steps 4 - 10

Step 4- splitting of 2 interconvertible 3 carbon molecules

Step 10- irreversible step conversion of phosphophenol pyravate to pyruvate

Steps 7 and 10 – produce ATP
• Produce 4 but have net gain of 2 ATP
• Substrate level phosphorylation – production of ATP by chemical reaction
• 1,3-BPG and PEP • Transfer Pi to ADP to give ATP

Answer 555

A

Steps 1,3 and 10 are irreversible

Can’t reverse glyodysis

Answer 556

A

Cleavage /splitting of C6 into two interconvertible C3 units
- c6 splits in either DHAP (dehydroxyacetone phosphate) or glyceraldehyde 3 phosphate (g3p) both are interconvertible c3 units
• C3 units interconvertible (occurs in reaction 5)
• C6 → 2C3 through phase 2

Answer 557

A

Phosphophenol pyruvate → pyruvate

Using pyruvate kinase enzyme
irreversible
produces ATP

Answer 558

A

2 moles of ATP put in at start of pathway
• 2 moles of ATP invested at the beginning to get the pathway going
• 4 moles of ATP produced per mole of glucose (2 x C3 processed)
= net of 2 ATP per mole of glucose

Answer 559

A

Glycerol phosphate (produced from DHAP)

- 2.3-bisphosphoglycerate (produced from 1,3 bisphosphoglycerate

Answer 560

A

Convert Dihydroxyacetone phosphate (DHAP) in adipose tissue and liver → Glycerol phosphate

glycerol phosphate is reactive – important for forming lipids (combine with 3 fatty acids) – store in adipocytes
• Important to triglyceride and phospholipid biosynthesis
• Therefore, lipid synthesis in liver requires glycolysis
• (Liver can phosphorylate glycerol directly) - to form glycerol phosphate that isn’t made from glycolysis

Answer 561

A

1,3-Bisphosphoglycerate in RBC → 2,3-Bisphosphoglycerate

Uses
• 2,3 BPG regulates oxygen affinity of haemoglobin
• Present in red blood cells (RBC) at the same molar concentration as haemoglobin (approx. 5 mM)

Answer 562

A

Chemistry Is easier to understand in smaller steps
1. Efficient energy conversation – small changes in molecules, not alot of bond breaking
2. Controlling point – controllable
3. Gives versatility
  – allows interconnections with other pathways
  – allows production of useful intermediates
  – allows part to be used in reverse

Answer 563

A

Pathway needs NAD+ to be converted to NADH for reducing power

• Total NAD+ and NADH in cell is constant, therefore, glycolysis would stop when all NAD+ is converted to NADH = fatal
- that shouldn’t happen as Normally NAD+ regenerated from NADH in stage 4 of metabolism oxidise NADH in etc

BUT
1. RBC have no stage 3 or 4 of metabolism – no mitochondria – can’t reform NAD+ directly
2. Stage 4 needs O2 - supply of O2 to muscles and gut often reduced
• Therefore, need to regenerate NAD+ by some other route

= lactate dehydrogenase can be used to reform NAD+

Answer 564

A

converts lactate –> pyruvate reforms NADH
• Reversible reaction can go from lactate to pyruvate or from pyruvate to lactate
• Reversible reaction depends on conditions demand
• Converting lactate -> pyruvate reforms NADH

Answer 565

A

Lactate produced by RBC and skeletal muscle (skin, brain, GI)
1. Released into blood - to deal with build up of lactate and
  • normally metabolised by liver and heart (via LDH) to remove lactate
2. Liver and heart need NAD+ to be regenerated quickly but have good oxygen supply

Answer 566

A

Lactic acid –> lactate ions and hydrogen ions = acidifying effects

blood acidosis
• When it acidifies the blood
• Metabolic acidosis – when lactate acidifies blood
• Lactate is measures in the blood

Normal lactate level in blood <1mM
Hyperlactaemia – high lactate 2-5mM
Lactic acidosis – above 5mM of lactate

Answer 567

A

Production → of lactate, more produced than removed
utilisation → How quickly liver, heart and muscle can get rid of lactate from blood
disposal→Excreting lactate using kidney

Answer 568

A

2-5mM
• Not much acidosis as there is no change in blood pH – blood has buffering capacity
• Below renal threshold – here level doesn’t exceed renal threshold so lactate can be reabsorbed and doesn’t appear in urine

Answer 569

A

above 5mM of lactate
• Above renal threshold - too much of lactate in blood can’t be reabsored (saturated) stays in filtrate and leaves via urine
• Blood pH lowered – large amount of lacatate overcomes blood buffering ability

Answer 570

A

reabsorption of things from filtrate can be saturated, too much of something in blood can’t be reabsored (saturated) stays in filtrate and leaves via urine

Answer 571

A

From glucose via pyruvate
from amino acid alanine• Normal lactate production 40-50g/24 hours

Plasma level of lactate can increase tenfold furong strenous exercsie including big meal – 30g/5min
• Plasma levels increase
• Return back to normal within 90 mins

Answer 572

A

Conditons where lactate level is elevated and stays elevated
• Shock – fall in bp
• Congestive heart disease – heart starts to fail and there is a build up of lactate

Answer 573

A

• Convert back to pyruvate
To be converted to acetyl coa and used in kreb cycle

• Convert into glucose in liver gluconeogenesis

.• heart muscle = LDH enzyme converts lactate –> pyruvate goes into kreb cycle acteyl coA – co2

Answer 574

A

Liver disease = insufficient metabolism of lactate
Deficiency of thiamine vitamins needed for this
Alcohol excessive dependence – uses up NAD+ l… do gluconeogenesis
Enzyme deficiences in population – genetic may
Prevent Gluconeogenesis

Answer 575

A

Regulated in response to demand

Allosteric control - activator/inhibitor binds at ‘another’ site

catalytic: promote formation of products
regulatory: binding of specific molecule, affects catalytic activity and can activate or inhibit

Covalent modification
• Dephoshphorylation or phosphorylation can activate or deactivate the enzyme

Answer 576

A

Step 1 -Hexokinase

Step 3 - Phosphofructokinase-1

Step 10 -Pyruvate kinase

Answer 577

A

Hexokinase
Glucose –> glucose 6 phosphate which feedbacks via product inhibition can reduce rate of first step and inhibit hexokinase

elevated levels of glucose 6 phosphate inhibits hexokinase
low levels of glucose 6 phosphate activates hexokinase

Answer 578

A

Phosphofructokinase-1

skeletal Muscle = depends on ATP:AMP ratio, allosteric inhibition

high ATP inhibits enzyme
low ATP stimulates enxyme = more pyruvate

Liver = insulin: glucagon
- high insulin = more glycolysis remove glucose and form glycogen

Answer 579

A

Pyruvate kinase

Insulin: glucagon ratio
- High insulin: glucagon ratio more glycolysis = less glucose
Dephosphorylation activates this enzyme

Answer 580

A

Fructose –> glucose 3 phosphate –> glycolysis

Galactose –> glucose 1 phosphate (can form glycogen for storage) –> glucose 6 phosphate —> glycolysis

Answer 581

A

Sucrose (refined sugars) = glucose + fructose

Fructose metabolised in liver
• Using fructokinase (move phosphate group to fructose) = Fructose –> fructose 1 phosphate
• Using aldolase to convert fructose 1 phosphate –> 2 glyceraldehyde 3 phosphate
• Use in glycolysis

Answer 582

A

Essential fructosuria - caused by fructokinase missing
• Fructose builds up in urine, exceed renal threshold and appears in urine no clinical signs

Fructose intolerance - aldolase missing =Buildup of fructose 1 phosphate and fructose in liver
• liver damage
• Treatment - remove fructose from diet
• Make too much fructose 1 phosphate not enough phosphate to make ATP
• No cure – genetic disorder

Answer 583

A

lactose milk sugar, = galactose and glucose

Galactose metabolised mainly in liver

• Galactose--> galactose 1 phosphate – using GALK (galactokinase)
• Galctose 1 phosphate --> glucose 1 phosphate – using GALT (galactose 1 phosphate puridyl transferase) - Missing GALT (galactose 1 phosphate puridyl transferase) = big problem
• UDP galactose 4 epidermase (GALE) – UDP glucose (acts catalytically) reaction to UDP galactose feeds into conversion above
• Deficient in read enzymes = galactosaemia

Answer 584

A

Elevated levels of galactose in blood

transferase deficiency = Accumulation of galactose and galactose 1 phosphate :

• High galactose levels – aldose reductase is activated 
• Galactose --> galactitol (alcohol version) via aldose reductase and use of NADPH - NADPH isa key defense against reactive oxygen radicals – reaction above depletes NADPh stores - Low NADPH = cells are defenseless against reactive ocygen species - Reactive oxygen species denatures critaslin protein in the lens of the eye = cataracts (cloudy lens)

• Accumulation of galactose 1 phosphate affects liver kidney and brain

Answer 585

A

Detect very early on ASAP after birth
- No cure
- Tretament is to avoid lactose in diet
- Still have cataracts but avoid other damage

Answer 586

A

Pyruvate does not directly enter stage 3 of catabolism

- must be converted to acetyl coa by pyruvate dehydrogenase enzyme

Answer 587

A

Pyravate → acetyl coa = irreversible reaction and carbon dioxide is lost

activated by:
• Pyruvate - a lot of pyruvate = more active
• NAD+ - lack of reducing power activates enzyme
• ADP – lack of energy activates enzyme
• Insulin
Activate enzyme by dephosphorylating it

inhibited by:
	• Acetyl coA
	• NADH
	• ATP
Inhibit enzyme by phosphorylating it

Answer 588

A

Inputs

Oxidative requires NAD+ and FAD which are reduced in cycle
acetyl coa

Outputs
One molecules of glucose produces:
	• 6NADH
	• 2FAD2H
	• 2GTP - some energy
Produces precursors for biosynthesis
Produces a lot of reducing power for stage

Answer 589

A

Citrate → fatty acids
succinate → haem groups
Oxaloacetate → glucose (or amino acids can form oxaloacetate and feed into cycle)
Alpha ketogutamate → amino acids

Answer 590

A

Isocitrate dehydrogenase
Isocitrate → alpha ketoglutarate

Ratio of ATP:ADP in cell and NAD+:NADH ratio
Activated by = high level of ADP, produces more electron donors stimulates cycle
Inhibited by = high level of NADH, as there are enough electron donors

Answer 591

A

Electron transport chain:

Electrons on NADH and FAD2H transferred through a series of carrier molecules to oxygen (ELECTRON TRANSPORT)
Releases energy in steps

Oxidative phosphorylation
- Free energy released from electrons used to drive ATP synthesis (OXIDATIVE PHOSPHORYLATION)

Answer 592

A

Cristae
inner membrane
outer membrane
Matrix

Inner mitochondrial membrane
• Largely permeable to water and ammonia
• Separate protons across the membrane
• Slightly leaky tho

Answer 593

A

→ oxidation of NADH and FAD2H - establish proton gradient, energy from released electrons is used to pump protons into intermembrane space
→ electrons are supplied to proton translocation complexes = pump protons

Large protein complexes span the membrane – these use the energy from the elctrons to pump protons across membrane into inner membrane space
Electrons move to second complex
Second complex has more electrons fed in by FAD2H – pump more protons
Electrons move to final complex
Build large proton gradient across membrane
Finally electrons combine with oxygen = water

Answer 594

A

Protons pass through ATP synthase enzyme when there is a significant gradient – energy from movement is used to make ATP
• Uses proton chemical concentration gradient
• Proton motive force – moving down conc gradient

NADH electrons have higher energy (uses 3 proton translocating complexes) – fed in earlier
- 2 NADH = 5 ATP
FAD2H electrons have lower energy ( use 2 proton translocating complexes) – fed in at lower level
- 2FAD2H = 3 ATP

Answer 595

A

NADH dehydrogenase = NADH –> NAD+ to release electrons
Coenzyme Q = shuffles electrons to the next protein complex

Side effect of statins
– reduce production of coenzyme Q = not good
• Cytochrome C – shuffles electrons to cytochrome oxidase
• Cytochrome oxidase = where electrons react with oxygen to give water
• Maintain large proton gradient

Answer 596

A

High ATP = low ADP – more difficult to make ATP as there is no ADP substrate that is used to form ATP
No process = inward flow of proton stops, concenttation gradient of protons builds up, harder to pump protons, slows process

Reversed = low ATP concentration, high ADP more protons pumped

Answer 597

A

Cyanide - can block etc
• Cyanide inhibits cytochrome oxidase enzyme
• Electrons aren’t added to oxygen – stop etc = no ATP = death
• Inhibitors block electron transport, e.g. cyanide (CN- ) prevents acceptance of electrons by O2

Answer 598

A

Normally oxidative phosphorylation and electron transport are tightly coupled → Operate conjointly
- Both regulated by mitochondrial [ATP] high ATP = no ADP inward proton flow stops, prevents pumping

Answer 599

A

→ Uncouplers increase the permeability of the mitochondrial inner membrane to protons = collapse gradient = reduce proton motive force

make it more leaky so protons don’t go through ATP synthase
no atp= death

Answer 600

A

Inhibition of electron transport
uncouples
ox/phos diseases

Answer 601

A

Block flow of electrons - no electron transport
therefore, no p.m.f. - no oxidative phosphorylation
Lethal – cyanide (inhibit cytochrome oxidase), carbon monoxide

Answer 602

A

May dissolve in membrane or act as transporters across membrane
- Dinitrocresol – herbicide = posion farmers
- Fatty acids – dissolve in membrane increasing permeability

Answer 603

A

Genetic defects in proteins encoded by mtDNA mitochondrial DNA (maternal line) = improper formation of complexes
- (some subunits of the PTCs and ATP synthase) → reduce speed in electron transport and ATP synthesis

Answer 604

A

→ Contains protein thermogenin (UCP1) uncoupling protein 1 - naturally-occurring uncoupling protein that collapses gradient = heat

Response to cold – release noradrenaline (maintain body temp) which activates:

Lipase which releases fatty acids from Triacylglycerol (fat stores)
Fatty acids activate UCP1. - more fatty acids = more FA oxidation → NADH/FAD2H → electron transport.
UCP1 transports H+ back into mitochondrial matrix – collapse proton gradient, make no TP, release heat
So, Electron Transport uncoupled from ATP Synthesis. Energy of p.m.f. is then captured as extra heat.

Method of making heat without producing ATP

Answer 605

A

Babies
• A lot of brown adipose tissue
• Allows them to maintain heat, particularly around vital organs

Adults do still have brown adipose tissue to maintain heat

Hibernating animals
• Over the winter
• so they can generate heat to maintain body temperature

Answer 606

A

Total 32 molecules of ATP from 1 molecule of glucose

• Most of the ATP comes from ETC

Answer 607

A

Lipid soluble, generally insoluble in water
- Most only contain C, H, O – (phospholipids contain P, N)

More reduced than carbohydrates
– release more energy when oxidised
– complete oxidation requires more O2
- get more energy from lipids than carbs

Answer 608

A

Fatty acid derivative.s
hydroxy-methyl-glutaric acid derivatives = c6 compound (hmgs)
Vitamins

Answer 609

A

Derived from fatty acids

fatty acids - fuel molecules
Triacylglycerols (triglycerides) basically fat – fuel storage and insulation
Phospholipids – components of membranes and plasma lipoproteins
Eicosanoids – local hormones/ mediators 20 carbons chain fatty acids eg. Prostoglandins

Answer 610

A

Ketone bodies (C4 ) – water soluble fuel molecules, transported in blood
Cholesterol (C27) – membranes and steroid hormone synthesis from cholesterol
Cholesterol esters – cholesterol storage, they are more lipid soluble forms of cholesterol used for transport in blood
Bile acids and salts (C24) – produced by liver, released by gall bladder lipid digestion (make fat breakdown easier)

Answer 611

A

A, D, E and K are fat soluble lipids

Answer 612

A

Made of glycerol (hydroxyl groups) and fatty acids (acidic group)

Esterification = acid groups react with hydroxyl alcohol group
- 3 fatty acids and 1 glycerol
Reversible reaction – lipolysis = breakdown triacyclglycerol into 3 glycerol and one fatty acid

Answer 613

A

Hydrophobic so they are stored in anhydrous form – droplets that don’t need lots of water
- Stored in adipose tissue
- These stores are only used in prolonged exercise, starvation and during pregnancy - after glucose and glycogen have been used up
- Storage and mobilisation of this fat is under hormonal control

Answer 614

A

Hydrolysis of triglycerides (lipids) occurs in gl tract → fatty acids and glycerol
Glycerol and fatty acids are absorbed into lymphatic system - and then absorbed into the blood
Glycerol is freely transported in blood (as it is polar) to the liver where it is metabolised
Fatty acids are not water soluble= transported by chylomicrons (lipoproteins) in the blood
Fatty acids are delivered to adipose tissue for storage - but can be remobilized by albumin

Answer 615

A

→ Fatty acids can be mobilized from adipose tissue – carried in blood to tissues for energy by binding to albumin
- Fatty acid can’t be used for energy in brain or by cells without mitochondria

• Controlled by hormone sensitive lipase
– breaks down fats into lipase but is under hormonal control
= insulin (promotes storage)
= glucagon/ adrenaline (stimulates breakdown of stores to be used for energy)

Answer 616

A

Formula: CH3(CH2)nCOOH where n= 14-18

* saturated – no double bond 
* unsaturated ( ie one or more double bonds C=C)  * amphipathic (contain hydrophilic (carboxylic acid end) & hydrophobic groups) polar and non polar

Fatty acids come from diet as we can’t manufacture them
certain polyunsaturated FA are essential (because mammals cannot introduce a double bond beyond C9), e.g. linolenic acid 18 : 3 (9,12,15)

Answer 617

A

Occurs in mitochondria
Fatty acid → acetyl coa

Also known as beta oxidation
Requires oxygen

Doesn’t occur in brain or cells without mitochondria

Answer 618

A

FA is activated – by linking FA (fatty acid) to coenzyme A outside of mitochondria, in cytosol
Must transport activated FA across mitochondria inner membrane – using carnitine shuttle ( transport mechanism)
FA goes through sequence of oxidative reactions in mitochondria – 2 carbons removed in each cycle until left with acetyl coA (to be used in kreb/ TCA cycle)
Oxidative process = This also produces FAD2h and NADH – electron donors for etc and oxidative phosphorylation

Answer 619

A

Binding coenzyme A to FA with high energy sulphide bond
- Uses enzyme fatty acycl coA synthase
- Forms fatty acyl coA – active form of FA
- Outside mitochondria in cytoplasm

Answer 620

A

→ transports activated fatty acid (fatty acyl coa) across inner mitochondrial membrane

Carnitine reacts with acyl coA – activated FA to give = acyl carnitine and coA
Acyl carnitine – fa bound to carnitine
That has a special transporter that transports acyl carnitine across membrane into matrix
Acyl carnitine is broken down into carnitine releasing acyl component which is converted back to acetyl coa
Carnitine shuffled back across membrane to be reused

Answer 621

A

CAT1/2 carnitine acyltransferases = synthesis and breakdown of acyl carnation
• Convert carnitine to acyl carnitine
• Convert acyl carnitine to carnitine

Malonyl coa
• shuttle Inhibited by malonyl coA
- it is an intermediate in FA production, stopping newly made FA being immediately oxidised

Answer 622

A

→ difficulty providing energy to muscles over a long period of time

* Exercise intolerance
* Lipid droplets in muscle

Answer 623

A

→ glycerol is transported to liver where it is metabolised

Form an active form of glycerol by recating with ATP = glycerol phosphate
• Using enzyme glycerol kinase – adding phosphate group to glycerol
Use glycerol phosphate in one of 2 ways
• Use it to form triacylglycerides – triacylglycerol synthesis fats for storage
• If there is demand it can be fed into glycolysis by being converted to dihydroxyacetone phosphate DHAP

Answer 624

A

Depends on energy demands

Use it to form triacylglycerides – fats for storage
If there is demand it can be fed into glycolysis by being converted to dihydroxyacetone phosphate DHAP ( and form NADH)

Answer 625

A

→ convergence point for anabolic and catabolic pathways
• Converted to fatty acids – anabolism
• Breakdown down of fatty acids – catabolism

Structure:
• Acetly coA = acetly group linked to coenzyme a via sulfide bond – high energy bond
• like an activated acetyl group
• CoA contains vitamin B5

Answer 626

A

used as an intermediate for Fatty acid synthesis = that can then form triglycerols and phospholipids
converted to Carbon dioxide – when oxidised in kreb cycle
Go into Hydroxymethyl glutaric acid pathway: that can either form ketone bodies or cholesterol which gives rise to steroid hormones (depends on demand)

Answer 627

A

Water soluble
permit high plasma concentrations
ketonuria= when above renal threshold, excreted in urine

Answer 628

A

• Acetoacetate

(produced in liver- breaks down spontaneously to give acetone)
CH3COCH2COO-• Acetone
(produced when acetoacetate is broken down spontaneously)
CH3COCH3
volatile, breathed out smelt on breath = sign for type 1 did bites• Beta hydroxybuterate
(produced in liver)
CH3CHOHCH2COO

Answer 629

A

Normal to have in blood at low levels = <1mM
Produce more ketone bodies under starvation conditions – so there are higher physiological levels (physiological ketosis) = 2-10mM
Pathological ketosis = level above 10mM happens in untreated type 1 diabetes – level of ketone bodies builds up to high and dangerous levels

Answer 630

A

→ synthesised by liver mitochondria

Convert acetyl coA to hydroxy methyl gluterol coA using enzyme synthase HMG-coA
HMG coA can either be:
• Converted to cholesterol with HMG coA reductase
• Lysed by lyase enzyme and converted to ketone bodies (acetoacetate, acetone, beta hydroxybutyrate)

Answer 631

A

Fatty acids are broken down to acetyl coA
Acetyl coA is converted to acetoacetate and beta hydroxybutyrate (ketone bodies)
These leave the cells and are carried in the blood as ketone bodies are water soluble
In blood acetoacetate are broken down into acetone
Acetone and beta hydroxybutyrate are taken up by tissues that need ketone bodies
Beta hydroxybutyrate is converted back to acetoacetate which is converted to acetyl coA - which goes into kreb cycle

Answer 632

A

—> ketone bodies = are a way of delivering acetyl coA from liver to tissues that need energy
Acetyl coA is too large to directly transport it

Answer 633

A

Regulated by insulin/ glucagon ratio

Insulin – storage hormone, eating enough, good insulin supply, storage of fuel molecules = occurs in fed state
Glucagon – breakdown hormone, not enough food low insulin levels, high glucagon levels, low ratio – mobilise ketone bodies – occurs in starvation

Answer 634

A

Starvation = low insulin: glucagon ratio

1. Acetyl coA to HMG coA 
2. Lyase enzyme activated forming ketone bodies
3. HMG coA reductase inhibited

Ketone body synthesis

Answer 635

A

Acetyl coA to HMG coA
Lyase enzyme activated forming ketone bodies
HMG coA reductase inhibited

Low insulin: glucagon ratio

Answer 636

A

High insulin to glucagon ratio
1. Lyase enzyme inhibited
2. HMG coA reductase enzyme stimulated – cholesterol synthesis
3. Favours anabolism – no need for ktone bodies

Answer 637

A

Act to inhibit HMG CoA reductase to reduce cholesterol synthesis

Answer 638

A

• Acetoacetate and β-hydroxybuterate are relatively strong organic acids →ketoacidosis - acidify blood at high levels can be fatal

Answer 639

A

genetic component
- Majority of patients have translocation between chromosome 9 and 22
- Results in a small chromosome = Philadelphia chromosome

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