Question 1

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 −ΔG of hydrolysis. 
B)  The thioester bond between succinate and CoA has a large −ΔG 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 −ΔG of hydrolysis. 
B)  The thioester bond between succinate and CoA has a large −ΔG 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.

Question 2

Roughly how many more ATP's can be produced via the complete aerobic oxidation of glucose compared to that produced by glycolysis alone?

Accepted Answer

A)  twice as much 
B)  five times as much 
C)  fifteen times as much 
D)  thirty-two times as much 
E)  none of these 
A)  twice as much 
B)  five times as much 
C)  fifteen times as much 
D)  thirty-two times as much 
E)  none of these

Question 3

The enzyme "aconitase" is also known as "condensing enzyme"

Accepted Answer

A) True 
 B)False

Question 4

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

Accepted Answer

A) True 
 B)False

Question 5

There is a cyclic reaction in which pyruvate becomes oxaloacetate. The oxaloacetate is converted to malate and then back to pyruvate. This cycle is important because:

Accepted Answer

A)  There is no net use or fixation of CO2 in this cycle. 
B)  NADH is converted to NADPH in this cycle. 
C)  There is no net oxidation or reduction in this cycle. 
D)  NADPH is converted to NADH in this cycle. 
E)  This is actually a wasteful pathway with no practical use. 
A)  There is no net use or fixation of CO2 in this cycle. 
B)  NADH is converted to NADPH in this cycle. 
C)  There is no net oxidation or reduction in this cycle. 
D)  NADPH is converted to NADH in this cycle. 
E)  This is actually a wasteful pathway with no practical use.

Question 6

When acetyl-CoA reacts with oxaloacetate to form citrate

Accepted Answer

A)  a new carbon-carbon bond is formed 
B)  an oxidative decarboxylation reaction takes place 
C)  a dehydration reaction takes place 
D)  a rearrangement takes place 
E)  none of these 
A)  a new carbon-carbon bond is formed 
B)  an oxidative decarboxylation reaction takes place 
C)  a dehydration reaction takes place 
D)  a rearrangement takes place 
E)  none of these

Question 7

Lipoic acid is a required vitamin in the human diet.

Accepted Answer

A) True 
 B)False

Question 8

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

Question 9

The order of compounds and intermediates found in the citric acid cycle is as follows:

Accepted Answer

A)  IsoCitrate → Aconitate → α-Ketoglutarate → Fumarate → Malate → Oxaloacetate 
B)  Aconitate → IsoCitrate → Oxaloacetate → α-Ketoglutarate → Malate → Fumarate 
C)  Aconitate → IsoCitrate → α-Ketoglutarate → Fumarate → Malate → Oxaloacetate 
D)  Aconitate → IsoCitrate → α-Ketoglutarate → Malate → Fumarate → Oxaloacetate 
E)  IsoCitrate → Aconitate → α-Ketoglutarate → Malate → Oxaloacetate → Fumarate 
A)  IsoCitrate → Aconitate → α-Ketoglutarate → Fumarate → Malate → Oxaloacetate 
B)  Aconitate → IsoCitrate → Oxaloacetate → α-Ketoglutarate → Malate → Fumarate 
C)  Aconitate → IsoCitrate → α-Ketoglutarate → Fumarate → Malate → Oxaloacetate 
D)  Aconitate → IsoCitrate → α-Ketoglutarate → Malate → Fumarate → Oxaloacetate 
E)  IsoCitrate → Aconitate → α-Ketoglutarate → Malate → Oxaloacetate → Fumarate

Question 10

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 11

Which of these enzymes is most similar to pyruvate dehydrogenase?

Accepted Answer

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

Question 12

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 13

The reaction in which malate is oxidized to oxaloacetate is not thermodynamically favored. It takes place because

Accepted Answer

A)  it is coupled to ATP hydrolysis. 
B)  it involves substrate-level phosphorylation. 
C)  the product is continuously used up in the next reaction of the cycle, which is thermodynamically favored. 
D)  it is coupled to a strong reduction. 
A)  it is coupled to ATP hydrolysis. 
B)  it involves substrate-level phosphorylation. 
C)  the product is continuously used up in the next reaction of the cycle, which is thermodynamically favored. 
D)  it is coupled to a strong reduction.

Question 14

A unique feature of the glyoxylate cycle is that it allows the organisms that possess this pathway to

Accepted Answer

A)  produce fats from carbohydrates. 
B)  produce carbohydrates from fats. 
C)  convert acetyl-CoA to pyruvate. 
D)  do all of the above. 
A)  produce fats from carbohydrates. 
B)  produce carbohydrates from fats. 
C)  convert acetyl-CoA to pyruvate. 
D)  do all of the above.

Question 15

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 16

Which of the following is a source of NADPH?

Accepted Answer

A)  the pentose phosphate pathway 
B)  a series of reactions in which oxaloacetate is reduced to malate followed by oxidative decarboxylation of the malate to pyruvate 
C)  both of the above 
D)  neither of these 
A)  the pentose phosphate pathway 
B)  a series of reactions in which oxaloacetate is reduced to malate followed by oxidative decarboxylation of the malate to pyruvate 
C)  both of the above 
D)  neither of these

Question 17

In muscle cells, the following reaction proceeds as written, i.e., from left to right, despite having ΔG°' ≈ +30 kJ/mol. How can this occur malate + NAD+ → oxaloacetate + NADH + H+

Accepted Answer

A)  It is obviously thermodynamically favored under standard conditions. 
B)  In the cell, it is kinetically favored, even though it's thermodynamically unfavored. 
C)  The concentration of malate must be higher than oxaloacetate for this reaction to occur in the cell. 
D)  [H+] must be higher in muscle than under standard conditions, thus altering ΔG°' to ΔG°. 
A)  It is obviously thermodynamically favored under standard conditions. 
B)  In the cell, it is kinetically favored, even though it's thermodynamically unfavored. 
C)  The concentration of malate must be higher than oxaloacetate for this reaction to occur in the cell. 
D)  [H+] must be higher in muscle than under standard conditions, thus altering ΔG°' to ΔG°.

Question 18

Which of the following enzymes is the only membrane-bound enzyme in the citric acid cycle?

Accepted Answer

A)  Aconitase. 
B)  IsoCitrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  Alpha-Ketoglutarate Dehydrogenase complex. 
A)  Aconitase. 
B)  IsoCitrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  Alpha-Ketoglutarate Dehydrogenase complex.

Question 19

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 20

One round of the citric acid cycle generates about ten equivalents of ATP.

Accepted Answer

A) True 
 B)False

Exam 19: The Citric Acid Cycle

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

Roughly how many more ATP's can be produced via the complete aerobic oxidation of glucose compared to that produced by glycolysis alone?

The enzyme "aconitase" is also known as "condensing enzyme"

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

There is a cyclic reaction in which pyruvate becomes oxaloacetate. The oxaloacetate is converted to malate and then back to pyruvate. This cycle is important because:

When acetyl-CoA reacts with oxaloacetate to form citrate

Lipoic acid is a required vitamin in the human diet.

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

The order of compounds and intermediates found in the citric acid cycle is as follows:

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 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?

The reaction in which malate is oxidized to oxaloacetate is not thermodynamically favored. It takes place because

A unique feature of the glyoxylate cycle is that it allows the organisms that possess this pathway to

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

Which of the following is a source of NADPH?

In muscle cells, the following reaction proceeds as written, i.e., from left to right, despite having ΔG°' ≈ +30 kJ/mol. How can this occur malate + NAD+ → oxaloacetate + NADH + H+

Which of the following enzymes is the only membrane-bound enzyme in the citric acid cycle?

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

One round of the citric acid cycle generates about ten equivalents of ATP.

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

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

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

In muscle cells, the following reaction proceeds as written, i.e., from left to right, despite having ΔG°' ≈ +30 kJ/mol. How can this occur malate + NAD⁺ → oxaloacetate + NADH + H⁺