BIOC 384-EXAM 4 UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
Question:
1. Identify the strongest (a) reductant, strongest (b) oxidant,
and (c) what is the ΔE in Volts of a redox reaction with O2
and ferredoxin (Fe2+) using the table below?
Answer:
(a) ferredoxin
(b) O2
(c) +1.25V
Question:
2. Calculate the ∆G°' of a redox reaction of alpha-ketoglutarate and fumarate under
standard conditions using the table below.
Answer:
-79.2kJ/mol
Question:
3. Pantothenic acid is essential for life because it is the
vitamin precursor to acetyl-CoA, which is a molecule that
Answer:
is a cofactor in the biosynthetic pathways that produce fatty acids, acetylcholine,
heme and cholesterol.
,Question:
4. 17:3617:54
sidebar interaction. Press tab to begin.
Identify the coenzyme that provides a reactive disulfide
that participates in the redox reaction in the active site of
pyruvate dehydrogenase.
NAD+
thiamine pyrophosphate
coenzyme A
lipoamide
Answer:
lipoamide
Question:
5. Arsenite affects the lipoamide coenzymes of the
pyruvate dehydrogenase reaction by
Answer:
covalently modifying the coenzyme
Question:
6. Which vitamin is the precursor to the coenzyme that
functions as a reductant in the pyruvate dehydrogenase
complex in the final setup of the reaction?
Answer:
riboflavin
Question:
7. The reaction catalyzed by ______________is the most
exergonic reaction in the citrate cycle.
Answer:
alpha-ketoglutarate dehydrogenase
Question:
8. It is also possible to calculate ΔGº' for the malate
dehydrogenase reaction using reduction potentials
instead of the mass action ratio. Using the table below,
calculate ∆G°' and determine if the conversion from
malate to oxaloacetate is favorable under standard
biochemical conditions.
Malate + NAD+ --> Oxaloacetate + H+ + NADH
∆G°' = -nF∆E°'
Answer:
+28.94 kJ/mol
, Question:
9. Which of the following statements are true regarding
reaction 4 of the citrate cycle?
A. This reaction is an oxidative decarboxylation reaction.
B. In the first step of this reaction, α-ketoglutarate is
transferred to the lipoamide group of an enzyme.
C. This reaction is mechanistically identical to the
pyruvate dehydrogenase reaction in that it uses the same
coenzymes and requires three distinct enzyme subunits.
D. An isomerization intermediate is key to this reaction.
Answer:
This reaction is an oxidative decarboxylation reaction.
This reaction is mechanistically identical to the pyruvate dehydrogenase reaction
in that it uses the same coenzymes and requires three distinct enzyme subunits.
Question:
10. left to right, top to bottom
A) -SH
B--> C coenzymes
D) top
E) bottom
Answer:
Label this diagram of the reaction catalyzed by the E2 component of pyruvate
dehydrogenase.
A) Reactive thiol group
B) Acetyl-dihydrolipoamide
C) Dihydrolipoamide
D) Coenzyme A (CoA)
E) Acetyl coenzyme A (acetyl-CoA)
CORRECT ANSWERS
Question:
1. Identify the strongest (a) reductant, strongest (b) oxidant,
and (c) what is the ΔE in Volts of a redox reaction with O2
and ferredoxin (Fe2+) using the table below?
Answer:
(a) ferredoxin
(b) O2
(c) +1.25V
Question:
2. Calculate the ∆G°' of a redox reaction of alpha-ketoglutarate and fumarate under
standard conditions using the table below.
Answer:
-79.2kJ/mol
Question:
3. Pantothenic acid is essential for life because it is the
vitamin precursor to acetyl-CoA, which is a molecule that
Answer:
is a cofactor in the biosynthetic pathways that produce fatty acids, acetylcholine,
heme and cholesterol.
,Question:
4. 17:3617:54
sidebar interaction. Press tab to begin.
Identify the coenzyme that provides a reactive disulfide
that participates in the redox reaction in the active site of
pyruvate dehydrogenase.
NAD+
thiamine pyrophosphate
coenzyme A
lipoamide
Answer:
lipoamide
Question:
5. Arsenite affects the lipoamide coenzymes of the
pyruvate dehydrogenase reaction by
Answer:
covalently modifying the coenzyme
Question:
6. Which vitamin is the precursor to the coenzyme that
functions as a reductant in the pyruvate dehydrogenase
complex in the final setup of the reaction?
Answer:
riboflavin
Question:
7. The reaction catalyzed by ______________is the most
exergonic reaction in the citrate cycle.
Answer:
alpha-ketoglutarate dehydrogenase
Question:
8. It is also possible to calculate ΔGº' for the malate
dehydrogenase reaction using reduction potentials
instead of the mass action ratio. Using the table below,
calculate ∆G°' and determine if the conversion from
malate to oxaloacetate is favorable under standard
biochemical conditions.
Malate + NAD+ --> Oxaloacetate + H+ + NADH
∆G°' = -nF∆E°'
Answer:
+28.94 kJ/mol
, Question:
9. Which of the following statements are true regarding
reaction 4 of the citrate cycle?
A. This reaction is an oxidative decarboxylation reaction.
B. In the first step of this reaction, α-ketoglutarate is
transferred to the lipoamide group of an enzyme.
C. This reaction is mechanistically identical to the
pyruvate dehydrogenase reaction in that it uses the same
coenzymes and requires three distinct enzyme subunits.
D. An isomerization intermediate is key to this reaction.
Answer:
This reaction is an oxidative decarboxylation reaction.
This reaction is mechanistically identical to the pyruvate dehydrogenase reaction
in that it uses the same coenzymes and requires three distinct enzyme subunits.
Question:
10. left to right, top to bottom
A) -SH
B--> C coenzymes
D) top
E) bottom
Answer:
Label this diagram of the reaction catalyzed by the E2 component of pyruvate
dehydrogenase.
A) Reactive thiol group
B) Acetyl-dihydrolipoamide
C) Dihydrolipoamide
D) Coenzyme A (CoA)
E) Acetyl coenzyme A (acetyl-CoA)
