Question 1

The reaction catalyzed by __________ is the most exergonic reaction in the citrate cycle.

Accepted Answer

A)  citrate synthase 
B)  fumarase 
C)  isocitrate dehydrogenase 
D)    -ketoglutarate dehydrogenase 
A)  citrate synthase 
B)  fumarase 
C)  isocitrate dehydrogenase 
D)    -ketoglutarate dehydrogenase

Question 2

Hypothesize how high concentrations of the following would either inhibit or activate the specific enzymes of the citrate cycle and the citrate cycle as a whole.
A.AMP
B.ATP
C.ADP

Accepted Answer

A.High levels of AMP would activate @#IMG-DLM&_TB6

Question 3

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

Question 4

Which enzyme in the citrate cycle is activated by CoA?

Accepted Answer

A)  pyruvate dehydrogenase 
B)  citrate synthase 
C)  isocitrate dehydrogenase 
D)    -ketoglutarate dehydrogenase 
A)  pyruvate dehydrogenase 
B)  citrate synthase 
C)  isocitrate dehydrogenase 
D)    -ketoglutarate dehydrogenase

Question 5

Identify the strongest reductant in the table below.

Accepted Answer

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

Question 6

Which reactions in the citrate cycle produce CO2?

Accepted Answer

A)  1 and 2 
B)  2 and 3 
C)  3 and 4 
D)  4 and 5 
A)  1 and 2 
B)  2 and 3 
C)  3 and 4 
D)  4 and 5

Question 7

Which reaction in the citrate cycle produces GTP?

Accepted Answer

A)  3 
B)  4 
C)  5 
D)  6 
A)  3 
B)  4 
C)  5 
D)  6

Question 8

Briefly describe the eight reactions from the citrate cycle,including the identity of the organic reactions and the energetic products.

Accepted Answer

In the first reaction,oxaloacetate under

Question 9

Coenzyme A does not readily cross the cell membrane.However,coenzyme A functions as an acyl carrier in the citrate cycle in the mitochondrial matrix.Explain how coenzyme A crosses the cell membrane to participate in the citrate cycle.

Accepted Answer

Coenzyme A is degraded in the gut to pan

Question 10

Calculate the   of a redox reaction of pyruvate and hydrogen under standard conditions using the table below.

Accepted Answer

A)  18.33 kJ/mol 
B)  36.66 kJ/mol 
C)  54.99 kJ/mol 
D)  73.32 kJ/mol 
A)  18.33 kJ/mol 
B)  36.66 kJ/mol 
C)  54.99 kJ/mol 
D)  73.32 kJ/mol

Question 11

Explain the effect a high concentration of NADH has on the citrate cycle.

Accepted Answer

High NADH implies that the cell does not

Question 12

The anaplerotic reaction catalyzed by pyruvate carboxylase requires which coenzyme?

Accepted Answer

A)  niacin 
B)  biotin 
C)  riboflavin 
D)  thiamine 
A)  niacin 
B)  biotin 
C)  riboflavin 
D)  thiamine

Question 13

In the citrate cycle,a high concentration of NADH would result in

Accepted Answer

A)  activation of citrate synthase. 
B)  inhibition of  -ketoglutarate dehydrogenase. 
C)  inhibition of fumarase. 
D)  activation of  -ketoglutarate dehydrogenase. 
A)  activation of citrate synthase. 
B)  inhibition of  -ketoglutarate dehydrogenase. 
C)  inhibition of fumarase. 
D)  activation of  -ketoglutarate dehydrogenase.

Question 14

Why is the    of the condensation of oxaloacetate and acetyl-CoA highly favorable?

Accepted Answer

A)  The addition of inorganic phosphate provides energy, resulting in the highly favorable nature of this reaction. 
B)  Allosteric regulations of the reaction cause a release of energy, making the reaction thermodynamically favorable. 
C)  The iron-sulfur cluster in the enzyme reduces the activation energy of the reaction, resulting in the favorable   
D)  The hydrolysis of the thioester bond in citryl-CoA results in the highly exergonic reaction. 
A)  The addition of inorganic phosphate provides energy, resulting in the highly favorable nature of this reaction. 
B)  Allosteric regulations of the reaction cause a release of energy, making the reaction thermodynamically favorable. 
C)  The iron-sulfur cluster in the enzyme reduces the activation energy of the reaction, resulting in the favorable   
D)  The hydrolysis of the thioester bond in citryl-CoA results in the highly exergonic reaction.

Question 15

Identify the coenzyme that provides a reactive disulfide that participates in the redox reaction in the active site of pyruvate dehydrogenase.

Accepted Answer

A)  NAD+ 
B)  coenzyme A 
C)  lipoamide 
D)  thiamine pyrophosphate 
A)  NAD+ 
B)  coenzyme A 
C)  lipoamide 
D)  thiamine pyrophosphate

Question 16

Which citrate cycle intermediate is siphoned off the citrate cycle during starvation?

Accepted Answer

A)  succinyl-CoA 
B)  malate 
C)    -ketoglutarate 
D)  fumarate 
A)  succinyl-CoA 
B)  malate 
C)    -ketoglutarate 
D)  fumarate

Question 17

Which reaction in the citrate cycle produces CO2?

Accepted Answer

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

Question 18

Explain why riboflavin is critical to the citrate cycle.

Accepted Answer

Riboflavin is the precursor to flavin ad

Question 19

The primary function of NAD+ in the citrate cycle is that it

Accepted Answer

A)  functions as an electron donor. 
B)  is oxidized to produce GTP. 
C)  acts as an electron acceptor. 
D)  phosphorylates ADP. 
A)  functions as an electron donor. 
B)  is oxidized to produce GTP. 
C)  acts as an electron acceptor. 
D)  phosphorylates ADP.

Question 20

Compare and contrast the anaplerotic nature of the pyruvate carboxylase reaction and the phosphoenolpyruvate carboxylase reaction.

Accepted Answer

Both reactions help replenish oxaloaceta

Exam 10: The Citrate Cycle

The reaction catalyzed by __________ is the most exergonic reaction in the citrate cycle.

Hypothesize how high concentrations of the following would either inhibit or activate the specific enzymes of the citrate cycle and the citrate cycle as a whole. A.AMP B.ATP C.ADP

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

Which enzyme in the citrate cycle is activated by CoA?

Identify the strongest reductant in the table below.

Which reactions in the citrate cycle produce CO2?

Which reaction in the citrate cycle produces GTP?

Briefly describe the eight reactions from the citrate cycle,including the identity of the organic reactions and the energetic products.

Coenzyme A does not readily cross the cell membrane.However,coenzyme A functions as an acyl carrier in the citrate cycle in the mitochondrial matrix.Explain how coenzyme A crosses the cell membrane to participate in the citrate cycle.

Calculate the of a redox reaction of pyruvate and hydrogen under standard conditions using the table below.

Explain the effect a high concentration of NADH has on the citrate cycle.

The anaplerotic reaction catalyzed by pyruvate carboxylase requires which coenzyme?

In the citrate cycle,a high concentration of NADH would result in

Why is the of the condensation of oxaloacetate and acetyl-CoA highly favorable?

Identify the coenzyme that provides a reactive disulfide that participates in the redox reaction in the active site of pyruvate dehydrogenase.

Which citrate cycle intermediate is siphoned off the citrate cycle during starvation?

Which reaction in the citrate cycle produces CO2?

Explain why riboflavin is critical to the citrate cycle.

The primary function of NAD+ in the citrate cycle is that it

Compare and contrast the anaplerotic nature of the pyruvate carboxylase reaction and the phosphoenolpyruvate carboxylase reaction.

Principles of Biochemistry

Physical Biochemistry: Energy Conversion,water,and Membranes

Nucleic Acid Structure and Function

Protein Structure

Methods in Protein Biochemistry

Protein Function

Enzyme Mechanisms

Cell Signaling Systems

Glycolysis: a Paradigm of Metabolic Regulation

Oxidative Phosphorylation

Photosynthesis

Carbohydrate Structure and Function

Carbohydrate Metabolism

Lipid Structure and Function

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Metabolic Integration

Dna Replication, repair, and Recombination

Rna Synthesis, processing, and Gene Silencing

Protein Synthesis, posttranslational Modification, and Transport

Gene Regulation

Filters

Which reactions in the citrate cycle produce CO₂?

Which reaction in the citrate cycle produces CO₂?

The primary function of NAD⁺ in the citrate cycle is that it