Quiz 12 Key
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1-3. What happens to liver cell glycogen metabolism when glucagon binds its receptor?
Question 2 enzymes are (P) glycogen phosphorylase and (S) glycogen synthase.

Is glycogen (D) degraded or (S) synthesized?

Is the regulated enzyme (P), (S), or (B) both?

Is regulation (A) allosteric, (C) covalent, or (B) both?

1.   D

2.   B

3. C

4-6. The pyruvate dehydrogenase complex catalyzes a multi-step reaction, including oxidizing FADH2. Focus just on this part of the reaction to answer the questions.

Which enzyme
(E1, E2, or E3)?

Name the product of this enzyme.

Which coenzyme is directly reduced?
(C) CoA; (F) FAD; (L) lipoate; (N) NAD+; (T) TPP

4. E3

5. NADH

6. N

7-10. Each molecule below is a reactant in the citric acid cycle. For each, draw the product and write the name of the product. Use the back if you need more room.


product is α-ketoglutarate


product is malate

1-3. What happens to liver cell glycogen metabolism when [glucose-6-phosphate] is high?
Question 1 enzymes are (P) glycogen phosphorylase and (S) glycogen synthase.

Is the regulated enzyme (P), (S), or (B) both?

Is regulation (A) allosteric, (C) covalent, or (B) both?

Is glycogen (D) degraded or (S) synthesized?

1. P

2. A

3. S

4-6. The pyruvate dehydrogenase complex catalyzes a multi-step reaction, including converting H2-lipoate → lipoate.   Focus just on this part of the reaction to answer.

Which enzyme
(E1, E2, or E3)?

Name the product of this enzyme.

Which coenzyme oxidizes dihydrolipoate?
(C) CoA; (F) FAD; (L) lipoate; (N) NAD+; (T) TPP

4. E3

5. NADH

6. F

7-10. Each molecule below is a reactant in the citric acid cycle. For each, draw the product and write the name of the product. Use the back if you need more room.


product is citrate


product is fumarate

1-3. What happens to skeletal muscle cell glycogen metabolism when [ATP] is high?
Question 2 enzymes are (P) glycogen phosphorylase and (S) glycogen synthase.

Is glycogen (D) degraded or (S) synthesized?

Is the regulated enzyme (P), (S), or (B) both?

Is regulation (A) allosteric, (C) covalent, or (B) both?

1. S

2. P

3. A

4-6. The pyruvate dehydrogenase complex catalyzes a multi-step reaction, including removing a carbon from pyruvate. Focus just on this part of the reaction.

Which enzyme
(E1, E2, or E3)?

Name the product of this enzyme.

Which coenzyme is directly required?
(C) CoA; (F) FAD; (L) lipoate; (N) NAD+; (T) TPP

4. E1

5. CO2

6. T

7-10. Each molecule below is a reactant in the citric acid cycle. For each, draw the product and write the name of the product. Use the back if you need more room.

1-3. What happens to skeletal muscle cell glycogen metabolism when epinephrine binds its receptor?
Question 1 enzymes are (P) glycogen phosphorylase and (S) glycogen synthase.

Is the regulated enzyme (P), (S), or (B) both?

Is regulation (A) allosteric, (C) covalent, or (B) both?

Is glycogen (D) degraded or (S) synthesized?

1. B

2. C

3. D

4-6. The pyruvate dehydrogenase complex catalyzes a multi-step reaction, including transferring C2 from one coenzyme to another. Focus just on this part of the reaction.

Which enzyme
(E1, E2, or E3)?

Name the product of this enzyme.

Which coenzyme is required for the transfer?
(C) CoA; (F) FAD; (L) lipoate; (N) NAD+; (T) TPP

4. E2

5. AcCoA

6. L

7-10. Each molecule below is a reactant in the citric acid cycle. For each, draw the product and write the name of the product. Use the back if you need more room.

Comment after grading: This evidently was a hard quiz. I accepted answers that are different from those shown. For example, malate, immediately above, can be converted into fumarate or into oxaloacetate. On the other hand, α-ketoglutarate can only be made into succinyl-CoA, so there were no alternative correct answers for that. If, however, you drew and correctly labeled succinate, you received credit for correctly naming the molecule.

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