Question 1

Which of the following vitamins and enzyme cofactors are used by the pyruvate dehydrogenase complex during oxidative decarboxylation?

Accepted Answer

A)  Lipoic Acid. 
B)  Niacin. 
C)  Pantothenic Acid. 
D)  Thiamine. 
E)  All of these 
A)  Lipoic Acid. 
B)  Niacin. 
C)  Pantothenic Acid. 
D)  Thiamine. 
E)  All of these E

Question 2

The acetyl group is carried on lipoic acid as

Accepted Answer

A)  an alcohol. 
B)  a thioester. 
C)  a phosphoanhydride. 
D)  an amide. 
A)  an alcohol. 
B)  a thioester. 
C)  a phosphoanhydride. 
D)  an amide. B

Question 3

Exhibit 19A The following compounds are all intermediates in the citric acid cycle.   Refer to Exhibit 19A. Which intermediate is formed from fumarate?

Accepted Answer

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

Question 4

The intracellular site of the glyoxylate cycle is

Accepted Answer

A)  glyoxysomes only. 
B)  glyoxysomes and lysosomes. 
C)  glyoxysomes and Golgi apparatus. 
D)  glyoxysomes and smooth endoplasmic reticulum. 
A)  glyoxysomes only. 
B)  glyoxysomes and lysosomes. 
C)  glyoxysomes and Golgi apparatus. 
D)  glyoxysomes and smooth endoplasmic reticulum.

Question 5

The conversion of citrate to isocitrate is remarkable because

Accepted Answer

A)  it is a condensation reaction. 
B)  a chiral center is introduced in a molecule that did not have one previously. 
C)  a dehydration reaction is involved. 
D)  the enzyme that catalyzes it has very little specificity. 
A)  it is a condensation reaction. 
B)  a chiral center is introduced in a molecule that did not have one previously. 
C)  a dehydration reaction is involved. 
D)  the enzyme that catalyzes it has very little specificity.

Question 6

In the classical equation for respiration:
Glucose + 6O2 --> 6CO2 + 6H2O, the following molecules are found directly in the citric acid cycle:

Accepted Answer

A)  O2 
B)  Glucose and O2 
C)  CO2 and H2O 
D)  all of these arae found directly in the citric acid cycle 
A)  O2 
B)  Glucose and O2 
C)  CO2 and H2O 
D)  all of these arae found directly in the citric acid cycle

Question 7

The citric acid cycle uses anaplerotic reactions to get rid of the many intermediates of the cycle that accumulate during catabolism of amino acids.

Accepted Answer

A) True 
 B)False

Question 8

A control point outside the citric acid cycle is the reaction catalyzed by

Accepted Answer

A)  the pyruvate dehydrogenase complex. 
B)  citrate synthetase. 
C)  isocitrate dehydrogenase. 
D)  the α -ketoglutarate dehydrogenase complex. 
A)  the pyruvate dehydrogenase complex. 
B)  citrate synthetase. 
C)  isocitrate dehydrogenase. 
D)  the α -ketoglutarate dehydrogenase complex.

Question 9

All but one of the enzymes of the citric acid cycle are found in this part of the mitochondrion:

Accepted Answer

A)  The outer membrane. 
B)  The inner membrane. 
C)  The mitochondrial matrix. 
D)  The intermembrane space. 
E)  It is not known where these enzymes are located. 
A)  The outer membrane. 
B)  The inner membrane. 
C)  The mitochondrial matrix. 
D)  The intermembrane space. 
E)  It is not known where these enzymes are located.

Question 10

Glyoxysomes are named for the fact that they contain the glyoxylate pathway.

Accepted Answer

A) True 
 B)False

Question 11

​ The pyruvate produced by glycolysis is first oxidized to _____.

Accepted Answer

A)  one carbon dioxide molecule and one acetyl group 
B)  two carbon dioxide molecules and four acetyl groups 
C)  three carbon dioxide molecules and three acetyl groups 
D)  four carbon dioxide molecules and six acetyl groups 
A)  one carbon dioxide molecule and one acetyl group 
B)  two carbon dioxide molecules and four acetyl groups 
C)  three carbon dioxide molecules and three acetyl groups 
D)  four carbon dioxide molecules and six acetyl groups

Question 12

The reactions in which succinate is converted to oxaloacetate are, in order

Accepted Answer

A)  an oxidation, a dehydration, and an oxidation 
B)  three successive oxidation reactions 
C)  an oxidative decarboxylation, a dehydration, and a condensation 
D)  a condensation, a dehydration, and an oxidative decarboxylation 
A)  an oxidation, a dehydration, and an oxidation 
B)  three successive oxidation reactions 
C)  an oxidative decarboxylation, a dehydration, and a condensation 
D)  a condensation, a dehydration, and an oxidative decarboxylation

Question 13

The citric acid cycle is the only metabolic pathway that can be used both as an anabolic and as a catabolic pathway.

Accepted Answer

A) True 
 B)False

Question 14

Which of the following is not a reaction occurring during oxidative decarboxylation of pyruvate?

Accepted Answer

A)  Removal of CO2. 
B)  Oxidation of an acetate group. 
C)  Addition of Coenzyme A to a 2-carbon fragment. 
D)  Reduction of NAD+ 
E)  All of these reactions take place during oxidative decarboxylation. 
A)  Removal of CO2. 
B)  Oxidation of an acetate group. 
C)  Addition of Coenzyme A to a 2-carbon fragment. 
D)  Reduction of NAD+ 
E)  All of these reactions take place during oxidative decarboxylation.

Question 15

Exhibit 19A The following compounds are all intermediates in the citric acid cycle.   Refer to Exhibit 19A. Which intermediate releases CO2 concurrent with oxidation?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  Both 1 and 3 
E)  Both 2 and 3 
A)  1 
B)  2 
C)  3 
D)  Both 1 and 3 
E)  Both 2 and 3

Question 16

When the citric acid cycle is not functioning, the most common fate of acetyl-CoA from sugar metabolism in humans is the formation of fatty acids or cholesterol.

Accepted Answer

A) True 
 B)False

Question 17

Which of these enzymes is most similar to pyruvate dehydrogenase?

Accepted Answer

A)  Alpha -Ketoglutarate Dehydrogenase complex. 
B)  Iso Citrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  None of these enzymes is similar to pyruvate dehydrogenase. 
A)  Alpha -Ketoglutarate Dehydrogenase complex. 
B)  Iso Citrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  None of these enzymes is similar to pyruvate dehydrogenase.

Question 18

In which cellular location do the majority of the reactions of the citric acid cycle take place?

Accepted Answer

A)  the cytosol. 
B)  the mitochondrial matrix. 
C)  the endoplasmic reticulum. 
D)  lysosomes. 
E)  none of these 
A)  the cytosol. 
B)  the mitochondrial matrix. 
C)  the endoplasmic reticulum. 
D)  lysosomes. 
E)  none of these

Question 19

Which of the following enzymes does not use NAD+ for oxidation?

Accepted Answer

A)  Alpha -Ketoglutarate Dehydrogenase complex. 
B)  Iso Citrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  All of these enzymes use NAD+ 
A)  Alpha -Ketoglutarate Dehydrogenase complex. 
B)  Iso Citrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  All of these enzymes use NAD+

Question 20

Release of succinate from succinyl-CoA can be coupled to GTP synthesis because:

Accepted Answer

A)  The amide bond between succinate and CoA has a large − Δ G of hydrolysis. 
B)  The thioester bond between succinate and CoA has a large − Δ G of hydrolysis. 
C)  The link between succinate and CoA involves an acid anhydride to phosphate. 
D)  Coenzyme A is a "high energy" compound, just like GTP. 
E)  None of these explains why GTP can be formed during this reaction. 
A)  The amide bond between succinate and CoA has a large − Δ G of hydrolysis. 
B)  The thioester bond between succinate and CoA has a large − Δ G of hydrolysis. 
C)  The link between succinate and CoA involves an acid anhydride to phosphate. 
D)  Coenzyme A is a "high energy" compound, just like GTP. 
E)  None of these explains why GTP can be formed during this reaction.

Exam 19: The Citric Acid Cycle

Which of the following vitamins and enzyme cofactors are used by the pyruvate dehydrogenase complex during oxidative decarboxylation?

The acetyl group is carried on lipoic acid as

Exhibit 19A The following compounds are all intermediates in the citric acid cycle. Refer to Exhibit 19A. Which intermediate is formed from fumarate?

The intracellular site of the glyoxylate cycle is

The conversion of citrate to isocitrate is remarkable because

In the classical equation for respiration: Glucose + 6O2 --> 6CO2 + 6H2O, the following molecules are found directly in the citric acid cycle:

The citric acid cycle uses anaplerotic reactions to get rid of the many intermediates of the cycle that accumulate during catabolism of amino acids.

A control point outside the citric acid cycle is the reaction catalyzed by

All but one of the enzymes of the citric acid cycle are found in this part of the mitochondrion:

Glyoxysomes are named for the fact that they contain the glyoxylate pathway.

​ The pyruvate produced by glycolysis is first oxidized to _____.

The reactions in which succinate is converted to oxaloacetate are, in order

The citric acid cycle is the only metabolic pathway that can be used both as an anabolic and as a catabolic pathway.

Which of the following is not a reaction occurring during oxidative decarboxylation of pyruvate?

Exhibit 19A The following compounds are all intermediates in the citric acid cycle. Refer to Exhibit 19A. Which intermediate releases CO2 concurrent with oxidation?

When the citric acid cycle is not functioning, the most common fate of acetyl-CoA from sugar metabolism in humans is the formation of fatty acids or cholesterol.

Which of these enzymes is most similar to pyruvate dehydrogenase?

In which cellular location do the majority of the reactions of the citric acid cycle take place?

Which of the following enzymes does not use NAD+ for oxidation?

Release of succinate from succinyl-CoA can be coupled to GTP synthesis because:

Biochemistry and the Organization of Cells

Water the Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins Enzymes

The Behavior of Proteins Enzymes Mechanisms and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids How Structure Conveys Information

Biosynthesis of Nucleic Acids Replication

Transcription of the Genetic Code the Biosynthesis of Rna

Protein Synthesis Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses Cancer and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism Cellular Signaling

Filters

In the classical equation for respiration: Glucose + 6O₂ --> 6CO₂ + 6H₂O, the following molecules are found directly in the citric acid cycle:

The pyruvate produced by glycolysis is first oxidized to _____.

Exhibit 19A The following compounds are all intermediates in the citric acid cycle. Refer to Exhibit 19A. Which intermediate releases CO₂ concurrent with oxidation?

Which of the following enzymes does not use NAD⁺ for oxidation?