Download CHE 4310 Fall 2011

CHE 4310 Fall 2011
Biochemistry Quiz Review VI
A general note: Short answer questions are just that, short. Writing a paragraph filled with every term
you can remember from class won’t improve your answer— just answer clearly, succinctly, and in your
own words.
1. The pyruvate produced by glycolysis has different ultimate fates depending on whether the
cell has access to oxygen or not. What are those alternate fates?
2. There are two reactions in glycolysis which involve the isomerization of an aldose to a
ketose or vice-versa. What enzymes catalyze those two reactions?
3. When glucose labeled with a 14C at C-1 passes through glycolysis, the glyceraldehyde 3phosphate that is produced from it still contains the radioactive carbon atom. Draw the
structure of glyceraldehyde 3-phosphate, and circle the atom(s) that would be radioactive.
4. When a mixture of 1,3-bisphosphoglycerate and 3-phosphoglycerate is incubated with the
enzyme phosphoglycerate kinase in the presence of an excess of DP and ATP, the final mixture
contains approximately 1750 molecules of 3-phosphoglycerate for every 1 molecule of 1,3bisphosphoglycerate. Estimate the G’0 of the reaction below (R = 8.315 J/mol·K and T = 298
K).
1,3-bisphosphoglycerate ↔ 3-phosphoglycerate
5. The pyruvate dehydrogenase complex performs complex functions in the cell. What are all
of the reactants and products of the PDC? Then, name three molecules that inhibit the activity
of the PDC.
6. Show the three reactions in the citric acid cycle in which NADH is produced, including the
structures. None of these reactions involves molecular oxygen (O2), but all three reactions
are strongly inhibited by anaerobic conditions; explain why.
7. You are in charge of genetically engineering a new bacterium that will derive all of its ATP
from sunlight by photosynthesis. Will you put the enzymes of the citric acid cycle in this
organism? Briefly explain why or why not.
8. Glucose labeled with 14C in C-3 and C-4 is completely converted to acetyl-CoA via
glycolysis and the pyruvate dehydrogenase complex. What percentage of the acetyl-CoA
molecules formed will be labeled with 14C, and in which position of the acetyl moiety will the
14
C label be found?
9. What is the reaction of the citric acid cycle that is most similar to the pyruvate
dehydrogenase complex-catalyzed conversion of pyruvate to acetyl-CoA?
10. The conversion of 1 mol of pyruvate to 3 mol of CO2 via pyruvate dehydrogenase and the
citric acid cycle yields what amount of NADH, FADH2, and ATP?
11. Glycolysis takes place primarily in the __________________, while the citric acid cycle
takes place primarily in the __________________.
12. Completing reactions. Fill in the blanks for each reaction with reactants, enzyme, or
products.
__________________

Succinate dehydrogenase
_____________________
____________________
_____________________

-ketoglutarate
dehydrogenase complex

_____________________
____________________
Phosphoenolpyruvate

Triose phosphate isomerase
_____________________

_____________________