Unit 1
Which molecular interaction is NOT considered a weak interaction:
A. Hydrogen bonds
B. Covalent bonds
C. Van der Waals interaction
D. Hydrophobic effect
E. Ionic interaction
B. covalent bonds
Is diffusion of glucose across an erythrocyte membrane an active or passive transport?
Passive
Glycolysis and gluconeogenesis are not simply the same pathway in reverse of each other. Which enzymatic steps differ between them?
Which of the following is a terminal electron acceptor?
A. NADH
B. NADPH
C. H2O
D. Pyruvate
D. Pyruvate
Which amino acid mutation is likely to be most detrimental to an organism?
A. Leu -> Ile
B. Asp -> Pro
C. Asp -> Glu
D. Arg -> Lys
B. Asp -> Pro
An enzyme with a high Km:
a. Also has a high Vmax
b. Has low affinity for its substrate
c. Is being affected by an uncompetitive inhibitor
d. Is monomeric
b. Has low affinity for its substrate
What is the primary purpose of the conversion of oxaloacetate into malate in the mitochondria, and subsequent oxidation of malate in the cytosol, during the Pyruvate -> PEP bypass of gluconeogenesis?
NADH is moved into the cytosol, needed to reverse GAPDH step.
Starting from Acetyl-CoA, how much CO2 is produced by the glyoxylate cycle?
A. 0
B. 1
C. 2
D. 3
What is the fold difference in [H+] between an aqueous solution at pH 7 and pH 6?
10 fold
What type of glycosidic bond(s) is found in glycogen? cellulose?
Glycogen: alpha 1-4 and 1-6
Cellulose: beta 1-4
How do erythrocytes maintain a constant flow of glucose into the cell?
Hexokinase phosphorylates glucose once it enters, "trapping" it in the cell.
Glycogen synthesis will most likely occur when:
A. Gluconeogenesis is also activated
B. Pyruvate is being fermented
C. Glycolysis is also activated
D. Blood sugar is low
C. Glycolysis is also activated
Which statement is true about hemoglobin and myoglobin binding carbon monoxide (C≡O) and molecular oxygen (O=O)?
a. Both oxygen and carbon monoxide bind equally tightly to the heme part of these proteins.
b. If it were not for the protein moiety of hemoglobin and myoglobin, C≡O would be more toxic to humans because binding would be even tighter
c. Oxygen fits much better into the hydrophobic binding site of hemoglobin and myoglobin.
d. C≡O only binds to the heme tightly when its partial pressure (concentration) in the air is higher than that of oxygen
e. The binding of carbon monoxide and carbon dioxide to myoglobin is approximately equal
b. If it were not for the protein moiety of hemoglobin and myoglobin, C≡O would be more toxic to humans because binding would be even tighter
Name the components of a nucleotide.
Sugar, phosphate, base
Glucagon is an activator of ___ in the _________:
a. Glycogen phosphorylase / muscle
b. Glycogen synthase/ muscle
c. Glycogen phosphorylase / liver
d. Glycogen synthase /liver
c. Glycogen phosphorylase / liver
Glucagon promotes glycogen breakdown in liver, does not have receptors in muscle
The fixation of 3 molecules of CO2 into 1 molecule of G3P requires:
A. 6 ATP and 6 NADPH
B. 12ATP and 12 NADPH
C. 9 ATP and 6 NADPH
D. 6 ATP and 6 NADP +
A. 6 ATP and 6 NADPH
What amino acids would you expect (or not expect) to see in A) a beta turn and B) an alpha helix?
beta turn: you would expect to see proline and glycine residues
alpha helix: you would expect to NOT see prolines and glycine, also you might see oppositely charged R groups n+4 residues apart
How many chiral carbons AND how many stereoisomers does glucose have?
4 chiral carbons
2^4 = 16 stereoisomers
What are two ways the ΔG of a reaction which is unfavorable under standard conditions can be made favorable under cellular conditions?
1) Couple a reaction with the hydrolysis of ATP, a very exergonic reaction.
2) Create an environment such that Q is very low (i.e. the concentration of products is much lower than the concentration of substrates)
If the pyruvate dehydrogenase complex is inactivated, what will be the effect on: Lactate production, mitochondrial matrix pH, and citrate production?
A. Increase, increase, decrease
B. Decrease, decrease, increase
C. increase, decrease, decrease
D. Increase, decrease, increase
E. Decrease, increase, decrease
C. If PDH is inhibited, TCA cycle will dramatically lessen so we will get:
Increased lactate (fermentation will occur to regenerate NAD)
Decreased pH relative to functioning TCA because substrates will not be pumped from the matrix to the inner membrane space
Decreased citrate production because we can't make TCA cycle substrates