Kaplan Biochem Contd. Flashcards
..: unit of DNA that encodes a specific protein or RNA molecule
gene
mRNA is synthesized in the … to … direction and is complementary and antiparallel to the DNA .. strand
5’; 3’; template
DNA template for transcription is the … to … strand
DNA … strand is the .. to … strand = identical to the mRNA transcript, except for the fact that DNA has thymine and RNA has uracil
3’; 5’
coding; 5’; 3’
ribosome translates mRNA in the … to … direction, synthesizing the protein from the … to … terminus
5’; 3’; N; C
…: only RNA that contains info translated into protein
transcribed from DNA by ..
mRNA; RNA polymerase
mRNA in eukaryotes is … –> one mRNA = one protein
mRNA in prokaryotes can be … –> one mRNA can code for several different proteins –> this can be achieved by having translation … in the mRNA to yield different proteins
monocistronic
polycistronic; start at different locations
transfer RNA (tRNA) contains a … and a … which recognizes and pairs with the appropriate codon on an mRNA transcript in the ribosome
folded strand of RNA: 3-nucleotide anticodon
transfer RNA:
activated/charged when …
mature tRNA are in the …
bonded to an amino acid
cytoplasm
transfer RNA
activated by …, which attaches amino acids to the 3’ end of the correct tRNA at the CCA nucleotide sequence –> activation requires … high E bonds from ATP, which implies that the bond between tRNA and aa is … (breaking it would release energy)
aminoacyl-tRNA synthetases
two
energy rich
the high energy aminoacyl-tRNA bond supplies energy needed to .. during translation
create peptide bonds
… is the primary component of ribosomes and is synthesized in the nucleolus
ribosomal RNA
rRNA can also function as … –> enzymes made of RNA
rRNA helps catalyze formation of … bonds and plays a role in … in the nucleus
ribozymes
peptide;
splicing out its own introns
there are … codons and the code is … –> one codon codes for only one amino acids
codons are written in .. to … direction
64; unambiguous
5’; 3’
61 codons code for one of the 20 amino acids and 3 code for …
termination of translation
the anticodon and codon are … to one another
antiparallel
every protein begins with …, so … is considered the start codon for translation
methionine; AUG
the way the anticodons stop termination is through the fact that there are no … that …, so it results in the ribosome releasing the protein
tRNAs; recognize them
stop codons: …, …, … –> mnemonics: …, …, …
UGA –> U Go Away
UAA –> U Are Annoying
UAG –> U Are Gone
genetic code is … because more than codon codes for the same amino acid. all amino acids except for … and … are encoded by more than one codon
degenerate; methionine; tryptophan
degenerate genetic code:
… bases are usually the same, and the … is variable –> this position is the … position, which helps protect against harmful mutations –> mutations in this position tend to be …/.. (having no effect)
first two; third
wobble
silent; degenerate
…: mutation that affects one of the nucleotides in a codon
… mutations
… mutation: one amino acid substitutes another
… mutation: early termination, aka … mutation
point mutation
silent
missense
nonsense; truncation
… mutations: insertions/deletions that change the reading frame –> more serious than point mutations
frameshift
translation occurs in the
cytoplasm
(transcription) DNA is unwound by … and … so that RNA polymerase has access to the sequence
template strand = …/… strand
coding strand = … strand
helicase; topoisomerase
antisense; missense
sense
(transcription) RNA polymerase locates the gene by … sequences –> in eukaryotes, this is the …
… help it locate and bind to these sequences
promoter; TATA box
transcription factors
RNA polymerase does not require …
primers
3 types of RNA polymerases in eukaryotes:
… –> in nucleolus, synthesizes rRNA
… –> in nucleus, synthesizes hnRNA (…) and some small nuclear RNA
… –> in nucleus, synthesizes tRNA and some rRNA
RNA polymerase I
RNA polymerase II: pre-mRNA
RNA polymerase III
RNA polymerase doesn’t ..
proofread
numbering system identifies location of important bases in the DNA strand in the vicinity of the gene –>
… is the first base transcribed, bases to the left of this (…, toward … end) are given … numbers and those the right (…, toward … end) are given … numbers
no nucleotide is assigned 0
TATA box is usually around …
\+1 upstream; 5' negative downstream; 3' positive -25
transcription continues until RNA polymerase reaches a …/.. –> results in …, called …, from which mRNA is derived after processing
termination sequence; stop signal
primary transcript; heterogenous nuclear RNA
introns, or non-coding sequences, are spliced out of the pre-mRNA using .., which consists of … coupled with proteins known as … (…)
spliceosome; small nuclear RNA; small nuclear ribonucleoproteins; snRNPs
snRNPs recognize both the 5’ and 3’ ends of the introns and cuts it out in the form of a … (…-shape) and subsequently … it
introns may be important for … regulation and maintaining …
lariat; lasso; degrades
gene expression; genome size
introns may allow for rapid
protein evolution
at 5’ end of hnRNA, a modified … (7-methylguanylate triphosphate cap) is added. this cap is added during … and is recognized by the ribosome as the …
protects mRNA from … in the cytoplasm
guanine
transcription
binding site
degradation
at 3’ end of hnRNA, a … (…) tail is added to protect against … in the cytoplasm
polyadenosyl; poly-A
degradation
longer poly-A tail = … mRNA will be able to survive before being degraded in the cytoplasm
poly A tail also helps facilitate … of mRNA from the …
more time
exit; nucleus
when the mRNA exits, there are still … (UTRs) that exist at both the 5’ and 3’ ends of the transcript, as the ribosome will start at the …and stop at a …
untranslated regions
start codon; termination sequencing
…: primary transcript of hnRNA can be spliced together in different ways to produce multiple variants of proteins encoded by the same original gene –> amplifies amount of proteins that can be made from a single gene, plays a role in regulation of …, and generates ..
alternative splicing
gene expression
protein diversity
mRNA transcript exits nucleus through …
nuclear pores
ribosome has … and … subunits that bind together during protein synthesis
large; small
ribosome has three binding sites for tRNA:
… site (…)
… site (…)
… site (…)
A; aminoacyl
P; peptidyl
E; exit
eukaryotic ribosomes have 4 strands of rRNA –> …, …, …, and …
28S; 18S; 5.8S; 5S
RNA polymerase I transcribes the …, …, and … rRNA as a single unit. this … unit sis processed such that the … rRNA becomes part of the .. small ribosomal subunit and the … and … rRNAs become part of the … large ribosomal subunit
28S; 18S; 5.8S
45S; 18S; 40S;
28S; 5.8S; 60S
RNA polymerase II transcribes … rRNA, which is also in the large subunit
5S
when the 60S and 40S subunits come together during translation, it forms an overall … ribosome
80S
prokaryotic ribosome has a … large subunit, a … small, and altogether it is …
50S; 30S; 70S
numbers of each subunit and each rRNA are not additive because they are based on … and …
size; shape
(initiation of translation)
… ribosomal subunit binds to the mRNA
in prokaryotes, binds to the … sequence
in eukaryotes, binds to the ..
small
Shine-Dalgarno
5’ cap
(initiation of translation)
initiator tRNA binds the start codon in the … site of the ribosome
initial amino acid in prokaryotes is …
in eukaryotes initial amino acid is …
P
N-formylmethionine
methionine
(initiation of translation)
… binds to the small subunit, assisted by …
large subunit; initiation factors
(elongation of translation)
3 step cycle repeated until termination
A site holds incoming … –> next amino acid being added to the growing chain
P site holds tRNA carrying the … –> peptide bond is formed as the polypeptide is passed from the tRNA in the p site to that in the A site –> facilitated by …, which is part of the large subunit, and … for energy
aminoacyl-tRNA
growing polypeptide chain
peptidyl transferase; GTP
(elongation of translation)
E site: where the … tRNA pauses temporarily before exiting the ribosome
… assist by locating and recruiting aminoacyl-tRNA along with …, while helping to remove … once energy has been used
inactivated
elongation factors
GTP
GDP
(elongation of translation) some eukaryotic proteins contain …, which designate a particular destination for the protein –> these are added …
signal sequences;
during translation
(elongation of translation) proteins being secreted will have signal sequences that direct the ribosome to move to the … so that it can be translated into the … and subsequently moved to … to be secreted in a vesicle
ER; lumen; Golgi
(elongation of translation) signal sequences can direct proteins to the …, …, or …
nucleus; lysosomes; cell membrane
(termination of translation)
when one of the stop codons moves into the A site, a protein called … binds to the codon, causing addition of a .. which allows … and … to hydrolyze the completed polypeptide chain from the final tRNA
polypeptide chain is released and ribosome dissociates
release factor
water molecule
peptidyl transferase; termination factors
after translation, proteins must .. and are assisted by …
fold; chaperone proteins
proteins can be modified by …
cleavage events
in peptides with quarternary structure, after translation, the subunits must
come together
other posttranslational processing:
…: addition of a phosphate group to activate/deactivate proteins –> common with …, …, and …
phosphorylation
serine; threonine; tyrosine
other posttranslational processing:
…: addition of carboxylic acid groups, usually to serve as calcium binding sites
…: addition of oligosaccharides as proteins pass through the ER and Golgi to determine cellular destination
…: addition of lipids to certain membrane-bound enzymes
carboxylation
glycosylation
prenylation
…: cluster of genes transcribed as a single mRNA –> prokaryotes
operon
Jacob Monod Model describes … and … of operons
structure; function
Jacob Monod Model:
…: codes for protein of interest
…: nontranscribable region of DNA where repressor protein binds; upstream of structural gene
…: upstream of operator site; provides a place for RNA polymerase to bind
…: furthest upstream, codes for the repressor protein
structural gene
operator site
promoter site
regulator gene
…: repressor is bonded tightly to the operator system to prevent gene expression
inducible systems
(inducible systems) ..: binding of a protein reduces transcriptional activity
an inducer can bind to the .. such that transcription will occur
negative control mechanisms
repressor
(inducible systems) higher conc of inducer means that more … of that gene will occur
transcription
(inducible systems) lac operon - present in E. Coli
E. coli can use lactose as food, but it is more energetically expensive than glucose digestion
When lactose concs are high and glucose is low, the lac operon is “turned on” such that.. can be generated
Assisted by binding of …which is a transcriptional activator used when glucose levels are low. Low glucose concs increases conc of cAMP, which binds to CAP and induces a conformational change that allows CAP to bind to the … to increase transcription of that agene
lactase; catabolite activator protein;
promoter of lac operon
(inducible systems) …: when binding of a molecule increases transcriptional activity
positive control mechanisms
…: allow constant production of a protein product
repressible systems
(repressible systems)
repressor made by the regulator gene is inactive until it binds to a … which facilitates its binding to the operator site
corepressor
(repressible systems) can function as … –> final product often acts as the corepressor, so that, as its levels increase, further transcription of that gene is inhibited
… operon: when tryptophan is present in the enviro in high concs, it acts as a … to prevent the cell from synthesizing its own tryptophan, which is energetically expensive
negative feedback;
Trp;
corepressor
…: transcription-activating proteins that have a DNA-binding domain and an activation domain
transcription factors
…: binds to a specific nucleotide sequence in the protomer region or to a response element to help recruit transcriptional machinery
DNA-binding domain
…: sequence of DNA that binds only to specific transcription factors
response element
…: allows for binding of several transcription factors and other regulatory proteins like polymerase and histone acetylases
activation domain
…: function in remodeling of chromatin structure
histone acetylases
genes have a basal level of transcription but expression can be amplified in response to certain signals –> accomplished through … and …
enhancers; gene duplication
…: several response elements grouped together to allow for control of gene expression
enhancer
enhancer:
signal molecules bind to receptors which are … that bind to their response elements within the enhancer
signal molecules: cAMP, cortisol, estrogen, etc
receptors: CREB, cortisol receptor, estrogen receptor
transcription factors
enhancer:
large distance between enhancer and promoter means that DNA must bend into a … to bring these elements together
enhancer region can be up to … bp away from the gene and can be in an intron
hairpin loop
1000
promoters must be within … of the start of a gene
25 bases
…: increase in gene expression by duplicating a gene
can be duplicated … to yield many copies in a row of the same genetic info
can be duplicated … by opening the gene with helicases and allowing for replication of just that gene, replicating until hundreds of copies of the gene exist … on the same chromosome
gene duplication
in series
in parallel
in parallel
… acetylatelysine residues in the amino terminal tail regions of histone proteins, which decreases the … on lysine and weakens interaction of histone with DNA –> opens chromatin such that it can be transcribed
histone acetylases; positive charge
histone deacetylases remove … groups from histones and are therefore components of …
acetyl; gene silencing
DNA … add methyl groups to .. and … –> linked with gene silencing
… much more heavily methylated
methylases; cytosine; adenine;
heterochromatin
carbs associated with membrane-bound proteins create a …
glycoprotein coat
the cell walls of plants, fungi, and bacteria, have higher levels of
carbs
… protect the internal enviro of the cell, control what enters and exits the cell, and plays a role in inter and intracellular communication
cell membranes
phospholipids move rapidly in the plane of the membrane through
simple diffusion
…; collections of similar lipids with/without associated proteins that serve as attachment points for other biomolecules –> often play roles in …
travel in the … of the membrane as well, but more slowly
lipid rafts
signaling
plane
lipids can flip between the membrane layers, but this is unfavorable bc the polar head would have to pass through the hydrophobic region –> facilitated by …
flippases
cells can … or … the number of cellular receptors in the cell membrane to meet cellular needs
up; downregulate
cell membrane has very few .. and contains …, … and … to maintain structural integrity
… provide membrane stability
free fatty acids; steroids; cholesterol; waxes
waxes
humans can only synthesize a few of the … and must consume the rest in their diets, which are then reabsorbed as chylomicrons in the small intestine
essential fatty acids: … and …
unsaturated fatty acids
alpha-linolenic acid; linoleic acid
saturated fatty acids … overall membrane fluidity where unsaturated fatty acids … it
decreae; increase
micelles are … vesicles whereas liposomes are …
monolayer; bilayered
… can produce a hydrophilic surface layer on …, which are proteins that transport lipids in the bloodstream
e.g. very-low-density lipoprotein
glycerophospholipids
lipoproteins
phospholipids can act as … in signal transduction
second messengers
phosphate group on phospholipids can act as a point of attachment for … such as choline
water soluble groups
… are also important constituents of cell membrane
sphingolipids
… essential for synthesis of all steroids
cholesterol
cholesterol … phospholipids but also occupies space between them –> contributes to its ability to regulate membrane fluidity
cholesterol prevents formation of … structures in membrane which increases fluidity at low temps
stabilizes
crystal
cholesterol is about 20% of cell membrane by … and about 50% by …
mass; mole fraction
waxes rarely found in cell membranes of .., but sometimes found in …
animals plants
waxes:
long chain … and long chain … –> have high melting pts
can provide … and … within nonpolar region of cell membrane
can have extracellular function of …/…
fatty acid; alcohol
stability; rigidity
protection; waterproofing
… proteins; pass completely through membrane
transporters, channels, receptors
transmembrane
…: only in the hydrophobic region of membrane
embedded proteins
…: transmembrane and embedded proteins –> association with interior usually assisted by … that are partially hydrophobic
integral proteins; membrane-associated domains
… (…) proteins may be bound through electrostatic interactions with lipid bilayer, esp at lipid rafts, or can be bound to transmembrane/embedded proteins
membrane-associated peripheral
bc carbs are hydrophilic, interactions between glycoproteins and water can form a … around the cell
coat
carbs on cell membrane can act as … and … molecules (e.g. ABO blodo types)
signaling; recognition
membrane receptors are typically …, but there are some carb and lipid ones, esp in viruses
proteins
… provide direct pathways of communication between cells or between cells and the extracellular matrix
comprised of … molecules, which enable recognition of cells and contribute to cell … and ..
cell-cell junctions
cell adhesion;
differentiation; development
… (…): found in small bunches together, formed by alignment and interaction of pores composed of six molecules of connexin
permit movement of … and some … between cells –> not really for protein transport between cells
gap junctions; connexons
water; solutes
…: prevent solutes from leaking into space between cells via .. route
found in epithelial cells and act as a … link between the cells as they form a single layer of tissue
limit permeability which can allow for a … based on differing concs of ions on either side of the epithelium
tight junctions;
paracellular;
physical;
transepithelial voltage difference
…: bind adjacent cells by anchoring to their cytoskeletons
desmosomes
desmosomes formed by interactions between … proteins associated with … inside adjacent cells
primarily found at interface between two layers of …
transmembrane proteins; intermediate filaments;
epithelial tissue
…: main function is to attach epithelial cells to underlying structures, esp the basement membrane
hemidesmosomes
desmosomes have more of an … purpose whereas tight junctions are aimed more at … from going in space …
attachment; preventing material; outside the cells
…, …, and … generally increase in rate as temp increases
diffusion; facilitated diffusion; osmosis
active transport may or may not increase in rate as temp increases –> depends on … of the process
enthalpy
primary thermodynamic motivator in most passive transport is … increase
entropy
…: substances move down their conc gradient directly across the membrane –> for molecules for which the membrane is permeable
… in a conc gradient is released during this process
simple diffusion;
potential energy
…: molecules move from a high water conc (dilute solution) to low water conc (conc solutoin) in an attempt to bring solute concentrations to …
osmosis
equimolarity
osmosis:
…: has less solute than cell
…: has more solute than cell
…: has equal solute as cell –> does not prevent movement altogether, but prevents net movement of particles across the membrane
hypotonic solution
hypertonic solution
isotonic solution
driving force behind osmosis can be quantified through …, a colligative property
osmotic pressure
….: physical property of solutions that is dependent on conc of dissolved particles but not on chemical identity of the dissolved particles
other examples: vapor pressure depression (Raoult’s Law), boiling point elevation, freezing point depression
colligative property
when osmosis is occurring across a semipermeable membrane that is impermeable to the solute, the concentrations of the solute in the two compartments …
Instead, water level will rise to the pt at which it exerts a sufficient pressure to counterbalance the tendency of water to …
can never be equal; flow across the membrane
osmotic pressure is defined by:
…
π=iMRT
M: molarity, R: ideal gas constant, T: absolute temp in K
i = van’t Hoff factor
i in osmotic pressure: van’t Hoff factor –> number of … obtained from the molecule when in solution
particles
in cells, … is maintained agains the cell membrane. so if osmotic pressure is too high for membrane to sustain, the cell will …
osmotic pressure
lyse
facilitated diffusion can involve carrier or channel proteins:
…: open only to one side of the cell membrane at any given point. binding of the substrate induces a conformational change, and for a brief period the carrier is … (not open to either side)
…: can be in a closed or open state. in their open conformation, they are exposed to both sides of the membrane
carriers; occluded
channels
…: uses ATP to directly power movement of a molecule across the membrane –> typically involves transmembrane …
used by neurons
primary active transport
ATPase
…/…: no direct coupling to ATP hydrolysis; powered by harnessing energy of one molecule moving down its gradient to drive a different molecule up its gradient
secondary active transport/coupled transport
coupled transport:
…: transport of both particles in the same direction
…: transport of the particles in opposite directions
used by .., typically driven by sodium, to reabsorb and secrete solutes into/out of filtrate
symport
antiport
kidneys
endocytosis:
…: endocytosis of fluids and dissolved particles
…: ingestion of large solids like bacteria
..: used to carry out endocytosis when substrates bind to specific receptors (a notable one of these is clathrin)
pinocytosis;
phagocytosis;
vesicle-coating proteins;
…: secretory vesicles fuse with membrane to release material from inside cell to extracellular enviro
exocytosis
…, Vm: difference in electrical potential across cell membranes
membrane potential
maintaining membrane potential requires energy bc ions may passively diffuse through the cell membrane over time using …
ion transporter or pump like … regulates conc of intracellular and extracellular sodium and potassium ions
… also participates in establishing membrane potential
leak channels
Na+/K+ ATPase
chloride
for goldman equation, chloride is inverted relative to the other ions bc it
carries a negative charge
sodium potassium ATPase aims to maintain … conc of sodium ions and … conc of potassium by pumping … out of the cell for every … that enters the cell –> remove … from intracellular space fo the cell, maintaining resting potential
low; high;
3 Na+; 2K+
one positive chare
cell membranes are more permeable to K+ at rest because there are ..
more K+ leak channels
…: highly permeable, completely surrounds inner mitochondrial membrane, with presence of intermembrane space between the two layers
outer mitochondrial membrane
…: more restricted permeability, has foldings known as cristae
o Encloses the mitochondrial …
o Contains very high level of … and does not contain …
Inner mitochondrial membrane;
matrix;
cardiolipid; cholesterol
normal blood glucose concentrations is … mM (range: … - … mM)
5.6; 4; 6
four glucose transporters, … through …
GLUT 1; GLUT 4
GLUT 2: low affinity transporter in … and … cells
captures … for storage
when glucose conc is below Km for GLUT 2, glucose bypasses … and enters …
hepatocytes; pancreatic
excess glucose
liver; peripheral circulation
GLUT 2:
liver will pick up glucose in proportion to its conc in the blood –> …
… uses GLUT 2 and glucokinase to act as a sensor for .. release
1st order kinetics;
beta islet cells of pancreas;
insulin
GLUT 4:
in … tissue and … and respond to blood glucose concs
rate of glucose transport is increased by …, which stimulates movement of additional GLUT 4 transporters to membrane by …
adipose; muscle
insulin
exocytosis
GLUT 4:
transporter is saturated when blood glucose levels are a bit … than normal
transporters follow … kinetics, so the only way for GLUT 4 to increase glucose intake is for there to be ….
higher
zero-order kinetics
more GLUT4 on the cell surface
GLUT 4:
muscle stores excess glucose as …
adipose tissue requires glucose to form …which is converted to glycerol phosphate to store fatty acids as triacylglycerols
glycogen
dihydroxyacetone phosphate
..: cytoplasmic pathway that converts glucose into two pyruvates, releasing some energy
can feed into … pathway to produce more energy
if mitochondria or oxygen is lacking, can occur …
provides … for other pathways such as fatty acid synthesis
glycolysis
aerobic respiration
anaerobically
intermediates
… adds a phosphoryl group to glucose once it enters the cytoplasm to generate … this makes the glucose more reactive and also prevents it from exiting the cell, since the GLUT transporters don’t recognize … glucose
hexokinase; glucose-6-phosphate;
phosphorylated
hexokinase is inhibited by …
…, which is specific to glucose, is found in liver cells and beta islet – unlike hexokinase, has a high Km (acts on glucose proportionally to its … ). This enzyme is induced by … in hepatocytes
G6P
glucokinase; conc; insulin
… is the rate limiting enzyme of glycolysis and catalyzes the conversion of … into … using ATP
phosphofructokinase-1
fructose-6-phosphate
fructose 1,6-bisphosphate
phosphofructokinase-1
inhibited by … and … and activated by … –> cell turns off glycolysis when there’s enough energy and turns it on when it needs energy; … is intermediate of citric acid cycle, so high concs indicate that sufficient energy is being generated
ATP; citrate; AMP; citrate
Phosphofructokinase-1 contd:
insulin indirectly stimulates PFK1 by activating … which converts a tiny amount of fructose 6-phosphate into … which activates PFK 1
… has the opposite effect
PFK2; fructose 2,6-bisphosphate;
glucagon
Phosphofructokinase-1 contd:
PFK 2 is mostly in the ..
this indirect activation/inhibition by insulin allows hepatocytes to override inhibition caused by … so that glycolysis can continue and its metabolites can be used for …, …, and other storage molecules’ production
liver; ATP; glycogen; fatty acids
… catalyzes an oxidation and addition of Pi to glyceraldehyde-3-phosphate to produce a high energy intermediate, …, and to reduce … to … –> this reduced product can be oxidized by the e- transport chain to provide more ATP
glyceraldehyde-3-phosphate dehydrogenase;
1,3-bisphosphoglycerate;
NAD+; NADH
… transfers high energy phosphate from 1,3-bisphosphoglycerate to ADP to form ATP and … –> ….: not dependent on oxygen and is consequently the only means of ATP production in anaerobic tissue
3-phosphoglycerate kinase; 3-phosphoglycerate;
substrate-level phosphorylation
… catalyzes substrate level phosphorylation of ADP using high energy …
activated by fructose 1,6-bisphosphate –> … activation
pyruvate kinase; phosphoenolpyruvate;
feed-forward
fermentation occurs in anaerobic conditions:
… oxidizes NADH to NAD+ to replenish the coenzyme for … –> prevents glycolysis from stopping under anaerobic conditions
in yeast, fermentation is the conversion of pyruvate to … and …, but the ultimate goal of replenishing … remains the same
lactate dehydrogenase; glyceraldehyde 3-phosphate dehydrogenase
ethanol; CO2; NAD+
(important glycolytic intermediates) ..: used in hepatic and adipose tissue for triacylglycerol synthesis
dihydroxyacetone phosphate
(important glycolytic intermediates) dihydroxyacetone phosphate formed when … is cleaved to … and …
can be isomerized to … which can be converted to …
fructose 1,6-bisphosphate; glyceraldehyde; DHAP
glycerol 3-phosphate; glycerol
(important glycolytic intermediates) … and … are the only intermediates through which ATP is gained by way of substrate level phosphorylation
1,3-bisphosphoglcyerate; phosphoenolpyrvuate
irreversible enzymes of glycolysis:
…
…
…
glucokinase/hexokinase
PFK-1
pyruvate kinase
since erythrocytes lack mitochondria, … is the only way they gain ATP
anaerobic glycolysis
glycolysis has a net gain of … ATP per glucose
2
RBCS have … which produces 2,3-bisphosphoglycerate from 1,3-BPG. 2,3-BPG binds allosterically to … of HbA and …
bisphosphoglycerate mutase;
beta chains;
decreases its affinity for oxygen
RBCs and 2,3-BPG activity:
facilitates … in tissues, but still allows for complete hemoglobin saturation in the lungs
2,3-BPG doesn’t bind well to fetal hemoglobin, which allows fetal hemoglobin to have … than maternal hemoglobin
oxygen unloading;
higher affinity for oxygen
… and … can also feed into glycolysis
galactose; fructose
… is an important dietary source of galactose –> hydrolyzed to galactose and glucose using … (brush border enzyme in duodenum
lactose; lactase
galactose reaches liver through … and can then be phosphorylated by … to form …, which can be converted to … by … and an epimerase
hepatic portal vein;
galactokinase;
galactose 1-phosphate;
glucose 1-phosphate; galactose-1-phosphate uridyltransferase
…: catalyze conversion of one epimer to another
epimerase
sucrose can be hydrolyzed by brush border enzyme … to yield … and …., which are then absorbed through hepatic portal vein. liver phosphorylates fructose using … to yield …, which is cleaved into … and … by …
sucrase; glucose; fructose;
fructokinase; fructose 1-phosphate;
glyceraldehyde; DHAP; aldolase B
pyruvate enters mito where it can be converted to … for entry into the citric acid cycle or for fatty acid synthesis –> catalyzed by …
acetyl-CoA
pyruvate dehydrogenase
pyruvate dehydrogenase complex rxn is …
irreversible
pyruvate dehydrogenase in liver is activated by …, but in the nervous system, it is not responsive to hormones
… levels signal to the liver that glucose is not needed (bc there is enough in bloodstream), and that there should be a shift towards … and … of fatty acids rather than oxidation
insulin;
high insulin;
production; storage
pyruvate can have 3 different fates:
conversion to … by …
conversion to … by …
conversion to … by …
acetyl CoA; pyruvate dehydrogenase
lactate; lactate dehydrogenase
oxaloacetate; pyruvate carboxylase
pyruvate dehydrogenase complex requires multiple cofactors and coenzymes: .... ... ... ... ...
thiamine pyrophosphate lipoic acid CoA FAD NAD+
pyruvate dehydrogenase is inhibited by … –> buildup of this leads to shift in metabolism in that pyruvate is no longer converted into … to enter citric acid cycle but instead is converted into … for …
acetyl-CoA;
acetyl CoA;
oxaloacetate
gluconeogenesis
glycogen is a storage form of glucose and is stored in cytoplasm as …
synthesis and degradation occur primarily in … and ….
granules
liver; skeletal muscle
glycogen granules have central protein core with … chains radiating outward to form a sphere
granules that have all linear chains have the highest density of glucose near the … whereas those that have branched chains will have the highest glucose density at the … of the granule –> … chains allow for more rapid glucose release
polyglucose chains
core
periphery
branched
glycogen in the liver acts as a source of glucose for when … is low and is quickly mobilized whereas glycogen in skeletal muscle is stored as …
blood sugar;
energy reserve for contraction
plants store excess glucose in … linked chains of glucose called …
alpha; starch
… is synthesis of glycogen granules –> begins with core protein …
glycogenesis;
glycogenin
glycogenesis
glucose begins as G6P and is converted to …, which is activated by coupling it to a molecule of …
G1P
uridine diphosphate
glycogenesis:
UDP permits glucose’s integration into the glycogen chain by …
glucose 1-phosphate is activated by interacting with … to form .. and …
glycogen synthase;
uridine triphosphate; UDP-glucose; pyrophasphate
glycogenesis:
…: rate-limiting enzyme of glycogen synthesis, forms the alpha 1,4 glycosidic bond in linear chains of glucose
stimulated by … and …
glycogen synthease;
G6P; insulin
glycogenesis
glycogen synthase inhibited by … and …, which causes a protein kinase cascade that phopshorylates and inactivates the enzyme –> these hormones indicate that glucose is needed in the bloodstream and therefore should not be incorporated into glycogen
epinephrine; glucagon
… introduces alpha 1,6-linked branches into glycogen granule as it grows:
the enzyme hydrolyzes one of the … bonds to release a block of … which is then moved and added in a slightly different location. the enzyme then forms an … bond to create a branch –> … will subsequently extend both the original and the new branch
branching enzyme alpha 1,4 oligoglucose alpha 1,6 bond glycogen synthase
…: process of breaking down glycogen
glycogenolysis
(glycogenolysis) Rate limiting enzyme is … (phosphorylases break bonds using an inorganic phosphate instead of water)
breaks … bonds to release … from periphery of granule
glycogen phosphorylase;
alpha 1,4-glycosidic bonds;
glucose 1-phosphate
(glycogenolysis) glycogen phosphorylase:
cannot break … bonds
activated by … in liver and … and … in skeletal muscle
inhibited by
alpha 1,6
glucagon; AMP; epinephrine;
ATP
