ACS biochemistry – Flashcards
Unlock all answers in this set
Unlock answersquestion
Describe the structural changes in hemoglobin that allow for cooperative binding of O2
answer
Binding of O2 in one subunit causes a conformational change in an adjacent subunit allowing O2 to bind
question
Which amino acids in "a" would be charged at pH 7?
answer
Asp, Glu, Arg, His, Lys
question
Which amino acids are negatively charged?
answer
Asp, Glu
question
which amino acids are positively charged?
answer
Arg, His, Lys
question
How are beta sheets stabilized in proteins?
answer
Hydrogen bonding between peptide backbone groups
question
Does myoglobin show cooperativity in O2 binding? If not, what structural differences account for this?
answer
Myoglobin does not show cooperativity because it is monomeric
question
What is a transition state inhibitor (how does its structure compare to the enzyme stubstrate?) how does its affinity for the enzyme compare to the enzyme's substrate?
answer
Similar to the substrate; binds to the active site with greater affinity than the substrate
question
would it be advantageous for these potential drugs to covalently bind to the enzyme? why or why not?
answer
Not advantageous because the urea cycle would shut down
question
From a practical standpoint, would it be advantageous for these potential drugs to be less chemically stable than the substrate?
answer
No, because of shelf life and time to reach target
question
In DNA, which bases hydrogen bond?
answer
A-T; G-C
question
In each base pair, how many hydrogen bonds are there?
answer
A-T=2; G-C=3
question
Which base-pair would require a higher temperature to destroy the hydrogen bonds?
answer
G-C
question
Based on the mechanism of alkaline hydrolysis of RNA, why is DNA less susceptible to alkaline hydrolysis?
answer
DNA lacks the 2' hydroxyl group
question
What is the difference between a reducing and nonreducing sugar?
answer
Reducing sugars have a free anomeric carbon that in the linear form can reduce an oxidizing agent.
question
what is a reducing monosaccharide?
answer
fructose or glucose
question
what is a reducing disaccharide?
answer
lactose
question
what is a nonreducing dissacharide?
answer
sucrose
question
what is a nonreducing monosaccharide?
answer
all monosaccharides are nonreducing
question
Why can't the peptide WYLVP be glycosylated in a glycoprotein?
answer
because it does not contain N, S, or T which are sites of glycosation (attachment of a carbohydrate)
question
Name three secondary messengers and what class of biomolecules they are derived from
answer
cAMP-nucleotide; IP3-lipid; DAG-lipid
question
What reactions occur during stage one of glycolysis?
answer
aldolase, F6P
question
What reactions occur during stage two of glycolysis?
answer
NADH formed, 3PG formed
question
name an allosteric regulator that can decrease glycolysis by inhibiting PFK
answer
ATP
question
What enzymes are unique to glycolysis?
answer
hexokinase, PFK, pyruvate kinase
question
what enzymes are unique to gluconeogenesis?
answer
glucose-6-phosphatase, fructose 1,6-biphosphatase, PEPCK carboxylase
question
what are the corresponding enzymes in glycolysis and gluconeogenesis
answer
pyruvate kinase is the corresponding enzyme in glycolysis for PEPCK and pyruvate carboxylase
question
what metabolic conditions can activate gluconeogenesis?
answer
low F6BP; high citrate; epinephrine/glucagon
question
what are the products of the pentose phosphate pathway?
answer
NADPH, ribose
question
List all the enzymes that use OAA as a substrate
answer
Pyruvate carboxylase, citrate synthase, malate dehydrogenase
question
what reaction is catalyzed by the coenzyme TPP (thiamine/B1)?
answer
Oxidative decarboxylation
question
What reaction is catalyzed by the coenzyme tetrahydrofolate (folic acid)?
answer
One carbon group transfer
question
what reaction is catalyzed by the coenzyme pyridoxal-5-phosphate (b6)
answer
Amino group transfer
question
what reaction is catalyzed by the coenzyme Cobalamin )B12)
answer
Alkylation
question
What reaction is catalyzed by the coenzyme lipoamide
answer
Transfer of an acetyl group to CoA
question
What is the chemiosmotic theory?
answer
Electron transport generates a proton gradient across the inner membrane due to H+ being pumped out; the energy released (proton motive force) when H+ returns to the matrix is used to power ATP synthesis
question
What are ketogenic substrates degraded to?
answer
acetyl CoA or ketone bodies
question
What are glucogenic substrates degraded to?
answer
pyruvate, alphaketoglutarate, succinyl CoA, fumarate, OAA
question
what is the equation to determine the number of cycles of B-oxidation of a saturated fatty acid?
answer
n/2-1
question
Describe what metabolic processes occur in the muscle and liver in the glucose-alanine cyvles during branched chain amino acid catabolism
answer
branched chain amino acids are degraded in the muscle and the NH3 is transported to the liver in the form of Ala. The liver uses the Ala for gluconeogenesis and the glucose is transported to the muscle for glycolysis.
question
what is an antagonist?
answer
binds to a receptor and prevents a response by keeping agonist from binding
question
what is an antagonist
answer
binds a receptor and causes a response
question
Is transverse or lateral diffusion in a lipid bilayer least likely to occur?
answer
transverse
question
If triglycerides and phospholipids are separated using TLC, what spot is more soluble (will be at the top)?
answer
tryglyceride; phospholipid will be less soluble so will not travel as far
question
In a gel filtration column, what proteins elute the quickest?
answer
the larger proteins that have a higher kDa elute first
question
what amino acid sequence is most likely to be in the core of a globular protein? why?
answer
ITFWLI; no charged amino acids and highest percent nonpolar
question
an example of a sticky restriction enzyme?
answer
A CGTGA
question
an example of a blunt restriction enzyme?
answer
ACG TGA
question
What is the function of TPP in the pyruvate dehydrogenase component of the pyruvate dehydrogenase complex?
answer
oxidative decarboxylation of pyruvate
question
what is the function of lipoamide in the dihydrolipoyl transacetylase portion of the pyruvate dehydrogenase complex?
answer
transfer of acetyl group to CoA
question
what is the function of FAD in the dihydrolipoyl portion of the pyruvate dehydrogenase complex
answer
regeneration of the oxidized form of lipoamide
