Question 1

The glyoxylate cycle occurs in

Accepted Answer

A)  plants and animals. 
B)  bacteria and animals. 
C)  plants and bacteria. 
D)  plants, animals, and bacteria. 
A)  plants and animals. 
B)  bacteria and animals. 
C)  plants and bacteria. 
D)  plants, animals, and bacteria. C

Question 2

Which coenzyme listed below is not associated with the α-ketoglutarate dehydrogenase complex?

Accepted Answer

A)  thiamine pyrophosphate 
B)  lipoic acid 
C)  biotin 
D)  NAD+ 
A)  thiamine pyrophosphate 
B)  lipoic acid 
C)  biotin 
D)  NAD+ C

Question 3

Which enzymes in the citric acid cycle catalyze oxidative decarboxylation reactions?

Accepted Answer

A)  isocitrate dehydrogenase and the α-ketoglutarate dehydrogenase complex 
B)  aconitase and succinate dehydrogenase 
C)  the α-ketoglutarate dehydrogenase complex and succinate thiokinase 
D)  fumarase and succinate dehydrogenase 
A)  isocitrate dehydrogenase and the α-ketoglutarate dehydrogenase complex 
B)  aconitase and succinate dehydrogenase 
C)  the α-ketoglutarate dehydrogenase complex and succinate thiokinase 
D)  fumarase and succinate dehydrogenase A

Question 4

Thiamine pyrophosphate carries a ____ carbon unit.

Accepted Answer

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

Question 5

"Energy charge" in a cell is a measure of

Accepted Answer

A)  ATP/NAD+ ratios. 
B)  ATP/NADH ratios. 
C)  ATP/ADP ratios. 
D)  NADH/NAD+ ratios. 
E)  NAD+/ADP ratios. 
A)  ATP/NAD+ ratios. 
B)  ATP/NADH ratios. 
C)  ATP/ADP ratios. 
D)  NADH/NAD+ ratios. 
E)  NAD+/ADP ratios.

Question 6

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

Question 7

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 8

The iron ion, which is part of succinate dehydrogenase, is bonded to heme.

Accepted Answer

A) True 
 B)False

Question 9

The citric acid cycle is amphibolic, meaning

Accepted Answer

A)  it plays a role in both anabolism and catabolism. 
B)  it is essentially irreversible. 
C)  it can operate both in the presence and absence of oxygen. 
D)  it can oxidize carbons and nitrogens equally well. 
E)  none of these 
A)  it plays a role in both anabolism and catabolism. 
B)  it is essentially irreversible. 
C)  it can operate both in the presence and absence of oxygen. 
D)  it can oxidize carbons and nitrogens equally well. 
E)  none of these

Question 10

The reaction of the citric acid cycle that does not take place in the mitochondrial matrix is the one catalyzed by:

Accepted Answer

A)  fumarase 
B)  citrate synthase 
C)  isocitrate dehydrogenase 
D)  succinate dehydrogenase 
E)  All of these reactions take place in the matrix 
A)  fumarase 
B)  citrate synthase 
C)  isocitrate dehydrogenase 
D)  succinate dehydrogenase 
E)  All of these reactions take place in the matrix

Question 11

In the conversion of succinyl-CoA to succinate, GTP is produced from GDP in a reaction in which the source of the added phosphate is

Accepted Answer

A)  ATP. 
B)  ADP. 
C)  phosphenolpyruvate. 
D)  inorganic phosphate ion. 
A)  ATP. 
B)  ADP. 
C)  phosphenolpyruvate. 
D)  inorganic phosphate ion.

Question 12

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 13

Which of the following enzymes is allosterically activated by NAD+?

Accepted Answer

A)  isocitrate dehydrogenase 
B)  succinyl-CoA synthetase 
C)  succinate dehydrogenase 
D)  fumarase 
E)  none of these 
A)  isocitrate dehydrogenase 
B)  succinyl-CoA synthetase 
C)  succinate dehydrogenase 
D)  fumarase 
E)  none of these

Question 14

The anaplerotic reactions associated with the citric acid cycle are the result of

Accepted Answer

A)  the oxidative nature of the citric acid cycle 
B)  the use of many of the citric acid cycle intermediates in anabolism 
C)  the decarboxylation reactions 
D)  the production of GTP and reduced coenzymes 
A)  the oxidative nature of the citric acid cycle 
B)  the use of many of the citric acid cycle intermediates in anabolism 
C)  the decarboxylation reactions 
D)  the production of GTP and reduced coenzymes

Question 15

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

Accepted Answer

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

Question 16

The production of malate in the glyoxylate pathway is important, since it can be readily converted to phosphoenolpyruvate and then to sugars.

Accepted Answer

A) True 
 B)False

Question 17

Which of the following reactions involves substrate-level phosphorylation?

Accepted Answer

A)  isocitrate → α-ketoglutarate 
B)  citrate → isocitrate 
C)  succinate → fumarate 
D)  succinyl-CoA → succinate 
E)  acetyl-CoA + oxaloacetate → citrate 
A)  isocitrate → α-ketoglutarate 
B)  citrate → isocitrate 
C)  succinate → fumarate 
D)  succinyl-CoA → succinate 
E)  acetyl-CoA + oxaloacetate → citrate

Question 18

Which of the following enzymes is not a control point of the citric acid cycle?

Accepted Answer

A)  citrate synthase 
B)  isocitrate dehydrogenase 
C)  aconitase 
D)  the α-ketoglutarate dehydrogenase complex 
A)  citrate synthase 
B)  isocitrate dehydrogenase 
C)  aconitase 
D)  the α-ketoglutarate dehydrogenase complex

Question 19

The enzymes involved in the pyruvate dehydrogenase complex are

Accepted Answer

A)  physically separated from each other 
B)  crosslinked to each other by lipoic acid linkers 
C)  covalently bonded to coenzyme A 
D)  associated with each other in an ordered and complex array 
A)  physically separated from each other 
B)  crosslinked to each other by lipoic acid linkers 
C)  covalently bonded to coenzyme A 
D)  associated with each other in an ordered and complex array

Question 20

The "energy charge" in a cell is important in the control of metabolism.

Accepted Answer

A) True 
 B)False

Exam 19: The Citric Acid Cycle

The glyoxylate cycle occurs in

Which coenzyme listed below is not associated with the α-ketoglutarate dehydrogenase complex?

Which enzymes in the citric acid cycle catalyze oxidative decarboxylation reactions?

Thiamine pyrophosphate carries a ____ carbon unit.

"Energy charge" in a cell is a measure of

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

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.

The iron ion, which is part of succinate dehydrogenase, is bonded to heme.

The citric acid cycle is amphibolic, meaning

The reaction of the citric acid cycle that does not take place in the mitochondrial matrix is the one catalyzed by:

In the conversion of succinyl-CoA to succinate, GTP is produced from GDP in a reaction in which the source of the added phosphate is

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

Which of the following enzymes is allosterically activated by NAD+?

The anaplerotic reactions associated with the citric acid cycle are the result of

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

The production of malate in the glyoxylate pathway is important, since it can be readily converted to phosphoenolpyruvate and then to sugars.

Which of the following reactions involves substrate-level phosphorylation?

Which of the following enzymes is not a control point of the citric acid cycle?

The enzymes involved in the pyruvate dehydrogenase complex are

The "energy charge" in a cell is important in the control of metabolism.

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: 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

Which of the following enzymes is allosterically activated by NAD⁺?

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