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 symport a type of active or passive transport?
Passive
Glycolysis and gluconeogenesis are not simply the same pathway in reverse of each other. What is it helpful for the cell to have key enzymatic steps differ between the two pathways?
Which of the following is a terminal electron acceptor?A. NADH
B. NADPH
C. H2O
D. Pyruvate
D. Pyruvate
Which is not true for a competitive inhibitor
A. Shares shape similarity with the substrate
B. Binds to the ES complex
C. Vmax is not altered
D. Competes with the substrate for the active site
B. Binds to the ES complex
A starch with 1-6 linkages is likely:
a. Undigestible for humans
b. An energy carrier
c. A branched sugar
d. Found only in plants
c. A branched sugar
What are the three irreversible enzymatic steps of glycolysis? Which is considered the commitment step for the pathway?
Hexokinase, Phosphofructokinase-1, Pyruvate Kinase.
Phophofructokinase -1 is the commitment 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
Is lactose a reducing sugar? What type of glycosidic linkage does it contain?
Yes! it has a free anomeric carbon
Beta 1-4 glycosidic linkage
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
Fructose-2,6-bis-phosphate is an activator of ___ in the _________:
a. Phosphofructo-kinase 1 / muscle
b. Fructose bis-phosphatase-1/ muscle
c. Phosphofructo-kinase 1 / liver
d. Fructose bis-phosphatase-1 /liver
c. Phosphofructo-kinase 1 / liver
Insulin activates PFK-2, which in turn activates PFK-1 to induce glycolysis in the liver
The fixation of 3 molecules of CO2 into 1 molecule of G3P requires:
6 ATP and 6 NADPH
12ATP and 12 NADPH
9 ATP and 6 NADPH
6 ATP and 6 NADP +
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