Question 1

According to the  Δ\DeltaΔ G  °\degree° ' , which of the following exergonic reactions is most likely irreversible under normal cellular conditions and is considered to be the rate-limiting step of the citrate cycle?

Accepted Answer

A)   "citrate synthase"
B)   "fumarase"
C)   "isocitrate dehydrogenase"
D)   " α\alphaα -ketoglutarate dehydrogenase"

Question 2

Compare the two ways the pyruvate dehydrogenase reaction is controlled by the cell.

Accepted Answer

Pyruvate dehydrogenase is regulated by a...

Question 3

Which enzyme in the citrate cycle produces NADH?

Accepted Answer

A)   aconitase
B)   citrate synthase
C)   isocitrate dehydrogenase
D)   fumarase

Question 4

Which reaction in the citrate cycle produces CO2? 2?   A)  1 B)  2 C)  3 D)  5" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   1
B)   2
C)   3
D)   5

Question 5

An in vitro study shows that citrate synthase is inhibited in the citrate cycle. What is a possible explanation for this inhibition?

Accepted Answer

A)   high levels of ADP
B)   low levels of succinyl-CoA
C)   high levels of NADH
D)   high levels of AMP

Question 6

Which enzyme regulates the flux of acetyl-CoA through the citrate cycle?

Accepted Answer

A)   "pyruvate dehydrogenase"
B)   "citrate synthase"
C)   "isocitrate dehydrogenase"
D)   " α\alphaα -ketoglutarate dehydrogenase"

Question 7

Classify the reaction that occurs at step 1 in the reaction schematic of the pyruvate dehydrogenase reaction below.

Accepted Answer

A)   isomerization
B)   addition
C)   oxidation reduction
D)   decarboxylation

Question 8

If acetyl-CoA is not metabolized by the citrate cycle, the molecule in the cell

Accepted Answer

A)   undergoes fatty acid metabolism.
B)   is transported across the cell membrane.
C)   is used to synthesize amino acids.
D)   is used during glycolysis. A

Question 9

Using the table below, calculate $\Delta$G $\degree$'  and determine if the conversion from malate to oxaloacetate is favorable under standard biochemical conditions.
Malate + NAD+ $\rightarrow$  Oxaloacetate + H+ + NADH

Accepted Answer

Calculate the<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30">E for the coupled redox rea...

Question 10

Pantothenic acid is essential for life because it is the vitamin precursor to the molecule that

Accepted Answer

A)   provides a reactive disulfide that can participate in redox reactions within the enzyme active site of pyruvate dehydrogenase.
B)   can accept one or two electrons in redox reactions in the cell.
C)   is involved in at least 200 redox reactions in the cell.
D)   is a cofactor in the biosynthetic pathways that produce fatty acids, acetylcholine, heme, and cholesterol. D

Question 11

Identify the strongest reductant in the table below. 2 B)  oxaloacetate C)  pyruvate D)  ferredoxin" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   O2
B)   oxaloacetate
C)   pyruvate
D)   ferredoxin

Question 12

Calculate the  Δ\DeltaΔ E  °\degree° '  of a coupled redox reaction with O2 and ferredoxin (Fe2+)  using the table below. '  of a coupled redox reaction with O2 and ferredoxin (Fe2+)  using the table below.   A)   -1.25  B)   -0.39  C)   0.39  D)   1.25  " class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   "-1.25"
B)   "-0.39"
C)   "0.39"
D)   "1.25"

Question 13

A high NADH to NAD+ ratio would inhibit which enzyme in the citrate cycle?

Accepted Answer

A)   succinate dehydrogenase
B)   succinyl-CoA synthetase
C)   aconitase
D)   isocitrate dehydrogenase

Question 14

What is the purpose of the first 3 steps in the pyruvate dehydrogenase reaction?

Accepted Answer

A)   regenerate the oxidized form of lipoamide
B)   form NADH
C)   transfer electrons
D)   form acetyl-CoA

Question 15

The primary function of the citrate cycle is to oxidize

Accepted Answer

A)   glucose.
B)   pyruvate.
C)   acetyl-CoA.
D)   citrate.

Question 16

Use the overall net reaction of the citrate cycle to explain why excess NADH inhibits the pyruvate dehydrogenase reaction.

Accepted Answer

NADH is a product in the balanced citrat...

Question 17

An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle. What is a possible explanation for the activation?

Accepted Answer

A)   high levels of ATP
B)   low levels of ATP
C)   high levels of NADH
D)   low levels of AMP B

Question 18

Which vitamin is the precursor to the coenzyme that functions as a reductant in the pyruvate dehydrogenase complex in the final step of the reaction?

Accepted Answer

A)   thiamine
B)   pantothenic acid
C)   riboflavin
D)   niacin

Question 19

The citrate cycle is considered to be a(n)  pathway.

Accepted Answer

A)   anabolic
B)   catabolic
C)   anaplerotic
D)   amphibolic

Question 20

What two features of the citrate cycle make it unique compared with linear metabolic pathways?

Accepted Answer

Oxaloacetate is both the substrate for t...

Exam 10: The Citrate Cycle

According to the $\Delta$ G $\degree$ ^' , which of the following exergonic reactions is most likely irreversible under normal cellular conditions and is considered to be the rate-limiting step of the citrate cycle?

Correct Answer
verified

Compare the two ways the pyruvate dehydrogenase reaction is controlled by the cell.

Correct Answer
verified
Pyruvate dehydrogenase is regulated by a...
View Answer

Which enzyme in the citrate cycle produces NADH?

Correct Answer
verified

Which reaction in the citrate cycle produces CO₂?

Correct Answer
verified

An in vitro study shows that citrate synthase is inhibited in the citrate cycle. What is a possible explanation for this inhibition?

Correct Answer
verified

Which enzyme regulates the flux of acetyl-CoA through the citrate cycle?

Correct Answer
verified

Classify the reaction that occurs at step 1 in the reaction schematic of the pyruvate dehydrogenase reaction below.

Correct Answer
verified

If acetyl-CoA is not metabolized by the citrate cycle, the molecule in the cell

Correct Answer
verified
A

Correct Answer
verified
Calculate theE for the coupled redox rea...
View Answer

Pantothenic acid is essential for life because it is the vitamin precursor to the molecule that

Correct Answer
verified
D

Identify the strongest reductant in the table below.

Correct Answer
verified

Correct Answer
verified

A high NADH to NAD⁺ratio would inhibit which enzyme in the citrate cycle?

Correct Answer
verified

What is the purpose of the first 3 steps in the pyruvate dehydrogenase reaction?

Correct Answer
verified

The primary function of the citrate cycle is to oxidize

Correct Answer
verified

Use the overall net reaction of the citrate cycle to explain why excess NADH inhibits the pyruvate dehydrogenase reaction.

Correct Answer
verified
NADH is a product in the balanced citrat...
View Answer

An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle. What is a possible explanation for the activation?

Correct Answer
verified
B

Which vitamin is the precursor to the coenzyme that functions as a reductant in the pyruvate dehydrogenase complex in the final step of the reaction?

Correct Answer
verified

The citrate cycle is considered to be a(n) pathway.

Correct Answer
verified

What two features of the citrate cycle make it unique compared with linear metabolic pathways?

Correct Answer
verified
Oxaloacetate is both the substrate for t...
View Answer

Exam 10: The Citrate Cycle

According to the Δ\DeltaΔ G °\degree° ' , which of the following exergonic reactions is most likely irreversible under normal cellular conditions and is considered to be the rate-limiting step of the citrate cycle?

Correct AnswerverifiedShow Answer

Compare the two ways the pyruvate dehydrogenase reaction is controlled by the cell.

Correct AnswerverifiedPyruvate dehydrogenase is regulated by a...View AnswerShow Answer

Which enzyme in the citrate cycle produces NADH?

Correct AnswerverifiedShow Answer

Which reaction in the citrate cycle produces CO2?

Correct AnswerverifiedShow Answer

An in vitro study shows that citrate synthase is inhibited in the citrate cycle. What is a possible explanation for this inhibition?

Correct AnswerverifiedShow Answer

Which enzyme regulates the flux of acetyl-CoA through the citrate cycle?

Correct AnswerverifiedShow Answer

Classify the reaction that occurs at step 1 in the reaction schematic of the pyruvate dehydrogenase reaction below.

Correct AnswerverifiedShow Answer

If acetyl-CoA is not metabolized by the citrate cycle, the molecule in the cell

Correct AnswerverifiedA

Using the table below, calculate Δ\DeltaΔ G °\degree° ' and determine if the conversion from malate to oxaloacetate is favorable under standard biochemical conditions. Malate + NAD+ →\rightarrow→ Oxaloacetate + H+ + NADH

Correct AnswerverifiedCalculate theE for the coupled redox rea...View AnswerShow Answer

Pantothenic acid is essential for life because it is the vitamin precursor to the molecule that

Correct AnswerverifiedD

Identify the strongest reductant in the table below.

Correct AnswerverifiedShow Answer

Calculate the Δ\DeltaΔ E °\degree° ' of a coupled redox reaction with O2 and ferredoxin (Fe2+) using the table below.

Correct AnswerverifiedShow Answer

A high NADH to NAD+ ratio would inhibit which enzyme in the citrate cycle?

Correct AnswerverifiedShow Answer

What is the purpose of the first 3 steps in the pyruvate dehydrogenase reaction?

Correct AnswerverifiedShow Answer

The primary function of the citrate cycle is to oxidize

Correct AnswerverifiedShow Answer

Use the overall net reaction of the citrate cycle to explain why excess NADH inhibits the pyruvate dehydrogenase reaction.

Correct AnswerverifiedNADH is a product in the balanced citrat...View AnswerShow Answer

An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle. What is a possible explanation for the activation?

Correct AnswerverifiedB

Which vitamin is the precursor to the coenzyme that functions as a reductant in the pyruvate dehydrogenase complex in the final step of the reaction?

Correct AnswerverifiedShow Answer

The citrate cycle is considered to be a(n) pathway.

Correct AnswerverifiedShow Answer

What two features of the citrate cycle make it unique compared with linear metabolic pathways?

Correct AnswerverifiedOxaloacetate is both the substrate for t...View AnswerShow Answer

According to the $\Delta$ G $\degree$ ^' , which of the following exergonic reactions is most likely irreversible under normal cellular conditions and is considered to be the rate-limiting step of the citrate cycle?

Correct Answer
verified

Correct Answer
verified
Pyruvate dehydrogenase is regulated by a...
View Answer

Correct Answer
verified

Which reaction in the citrate cycle produces CO₂?

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
verified

Correct Answer
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A

Correct Answer
verified
Calculate theE for the coupled redox rea...
View Answer

Correct Answer
verified
D

Correct Answer
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Correct Answer
verified

A high NADH to NAD⁺ratio would inhibit which enzyme in the citrate cycle?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
NADH is a product in the balanced citrat...
View Answer

Correct Answer
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B

Correct Answer
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Correct Answer
verified

Correct Answer
verified
Oxaloacetate is both the substrate for t...
View Answer