Question 1

Transamination reactions can be used to provide intermediates for the citric acid cycle.

Accepted Answer

A) True 
 B)False  True

Question 2

Which of the following enzymes catalyzes a reaction of the citric acid cycle that does NOT produce reduced electron carriers?

Accepted Answer

A)   Malate dehydrogenase
B)   Succinate dehydrogenase
C)   α-ketoglutarate dehydrogenase
D)   Isocitrate dehydrogenase
E)   Succinyl -CoA synthetase E

Question 3

The citric acid cycle can be considered both a ________ and anabolic pathway as it is used to oxidise acetyl CoA to carbon dioxide as well as to provide precursors for other ________ pathways.

Accepted Answer

catabolic, biosynthetic

Question 4

The two carbon atoms that are lost as CO2 in the third and fourth steps of the citric acid cycle are the same as the two carbon atoms of acetyl CoA because of the stereochemistry of the isocitrate dehydrogenase reaction.

Accepted Answer

A) True 
 B)False

Question 5

Which of the following techniques can be used to quantify protein-protein interactions?

Accepted Answer

A)   Co-immunoprecipitation
B)   Affinity chromatography
C)   Chemical cross-linking
D)   Surface plasmon resonance
E)   The two-hybrid system

Question 6

All of the enzymes of the citric acid cycle are located in the mitochondrion.

Accepted Answer

A) True 
 B)False

Question 7

NAD+, coenzyme A, thiamine pyrophosphate, lipoic acid and FAD are all cofactors used in the reaction catalyzed by pyruvate dehydrogenase.

Accepted Answer

A) True 
 B)False

Question 8

Which of the following does NOT regulate flux through the citric acid cycle?

Accepted Answer

A)   Substrate availability
B)   The ratio of [NAD+]/[NADH]
C)   Allosteric inhibition of isocitrate dehydrogenase by ADP
D)   Inhibition of α-ketoglutarate dehydrogenase by succinyl CoA
E)   Ca2+ activation of isocitrate dehydrogenase

Question 9

Arsenic poisoning acts by inhibiting the citric acid cycle at the point of both pyruvate dehydrogenase and α-ketoglutarate dehydrogenase because it makes a stable adduct with the ________ groups of the dihydrolipoamide intermediate.

Accepted Answer

The answer of Arsenic poisoning acts by inhibiting the citric...

Question 10

The citric acid cycle is classed as a reductive pathway as it produces reduced electron carriers.

Accepted Answer

A) True 
 B)False

Question 11

Oxaloacetate is replenished via the ________ in plants and bacteria.

Accepted Answer

The answer of Oxaloacetate is replenished via the ________ in...

Question 12

The glyoxylate cycle in plants and bacteria can be used for net carbohydrate synthesis from fat because isocitrate lyase yields glyoxylate and ________ without the loss of two carbons as occurs in the citric acid cycle.

Accepted Answer

The answer of The glyoxylate cycle in plants and bacteria...

Question 13

Taking one mole of glucose through glycolysis and the citric acid cycle generates:

Accepted Answer

A)   6C02, 8 NADH/H+, 1FADH2 and 1 ATP.
B)   6C02, 8 NADH/H+, 1FADH2 and 2 ATP.
C)   6C02, 10 NADH/H+, 2FADH2 and 2 ATP.
D)   6C02, 10 NADH/H+, 2FADH2 and 4 ATP.
E)   6C02, 8 NADH/H+, 2FADH2 and 4 ATP.

Question 14

Acetyl CoA is a feed forward activator of the enzyme ________ ensuring sufficient oxaloacetate for the citric acid cycle to continue.

Accepted Answer

The answer of Acetyl CoA is a feed forward activator...

Question 15

Which of the following does NOT apply to the reaction catalyzed by the pyruvate dehydrogenase complex?

Accepted Answer

A)   The process is highly exergonic and essentially irreversible in vivo.
B)   Each intermediate in the five step reaction is able to diffuse to the next active site in a sequential manner.
C)   It takes place in the mitochondrion.
D)   It is an oxidative decarboxylation.
E)   The product is acetyl CoenzymeA.

Question 16

One substrate level phosphorylation occurs in the citric acid cycle in the reaction catalyzed by:

Accepted Answer

A)   α-ketoglutarate dehydrogenase.
B)   succinate dehydrogenase.
C)   succinyl -CoA synthetase.
D)   isocitrate dehydrogenase.
E)   citrate synthase.

Question 17

The malate dehydrogenase reaction has a strongly positive standard free energy change but it proceeds in the direction of oxaloacetate because the concentration of ________ is maintained at exceedingly low levels.

Accepted Answer

The answer of The malate dehydrogenase reaction has a strongly...

Exam 13: The Citric Acid Cycle

Transamination reactions can be used to provide intermediates for the citric acid cycle.

Which of the following enzymes catalyzes a reaction of the citric acid cycle that does NOT produce reduced electron carriers?

The citric acid cycle can be considered both a and anabolic pathway as it is used to oxidise acetyl CoA to carbon dioxide as well as to provide precursors for other pathways.

The two carbon atoms that are lost as CO2 in the third and fourth steps of the citric acid cycle are the same as the two carbon atoms of acetyl CoA because of the stereochemistry of the isocitrate dehydrogenase reaction.

Which of the following techniques can be used to quantify protein-protein interactions?

All of the enzymes of the citric acid cycle are located in the mitochondrion.

NAD+, coenzyme A, thiamine pyrophosphate, lipoic acid and FAD are all cofactors used in the reaction catalyzed by pyruvate dehydrogenase.

Which of the following does NOT regulate flux through the citric acid cycle?

Arsenic poisoning acts by inhibiting the citric acid cycle at the point of both pyruvate dehydrogenase and α-ketoglutarate dehydrogenase because it makes a stable adduct with the ________ groups of the dihydrolipoamide intermediate.

The citric acid cycle is classed as a reductive pathway as it produces reduced electron carriers.

Oxaloacetate is replenished via the ________ in plants and bacteria.

The glyoxylate cycle in plants and bacteria can be used for net carbohydrate synthesis from fat because isocitrate lyase yields glyoxylate and ________ without the loss of two carbons as occurs in the citric acid cycle.

Taking one mole of glucose through glycolysis and the citric acid cycle generates:

Acetyl CoA is a feed forward activator of the enzyme ________ ensuring sufficient oxaloacetate for the citric acid cycle to continue.

Which of the following does NOT apply to the reaction catalyzed by the pyruvate dehydrogenase complex?

One substrate level phosphorylation occurs in the citric acid cycle in the reaction catalyzed by:

The malate dehydrogenase reaction has a strongly positive standard free energy change but it proceeds in the direction of oxaloacetate because the concentration of ________ is maintained at exceedingly low levels.