Question 1

During the oxidation of isocitrate, _____ is decarboxylated to form $\alpha$-ketoglutarate.

Accepted Answer

A) hydroxyethyl-TPP 
B) carboxybiotin 
C) oxalosuccinate 
D) succinyl-phosphate 
E) none of the above 
A) hydroxyethyl-TPP 
B) carboxybiotin 
C) oxalosuccinate 
D) succinyl-phosphate 
E) none of the above

Question 2

Which of the following citric acid cycle intermediates can be converted to aspartate via transamination?

Accepted Answer

A) citrate 
B) ($\alpha$-ketoglutarate) 
C) succinate 
D) fumarate 
E) oxaloacetate 
A) citrate 
B) ($\alpha$-ketoglutarate) 
C) succinate 
D) fumarate 
E) oxaloacetate

Question 3

One turn of the citric acid cycle generates

Accepted Answer

A) 2 FADH2, 3 ATP, 1 NADH 
B) 1 NAD+, 2FADH2, 1 ATP 
C) 1 GTP, 3 NADH, 1 FADH2 
D) 1 FAD, 2 ATP, 3 NADH 
E) 1 FADH2, 1GTP, 2 NADH 
A) 2 FADH2, 3 ATP, 1 NADH 
B) 1 NAD+, 2FADH2, 1 ATP 
C) 1 GTP, 3 NADH, 1 FADH2 
D) 1 FAD, 2 ATP, 3 NADH 
E) 1 FADH2, 1GTP, 2 NADH

Question 4

Which of the following causes pyruvate dehydrogenase kinase to catalyze the phosphorylation and inactivation of E1 in the pyruvate dehydrogenase complex?

Accepted Answer

A) elevated concentrations of NADH and ATP 
B) elevated concentrations of NAD+ and ADP 
C) insulin 
D) elevated concentrations of acetyl-CoA 
E) C and D 
A) elevated concentrations of NADH and ATP 
B) elevated concentrations of NAD+ and ADP 
C) insulin 
D) elevated concentrations of acetyl-CoA 
E) C and D

Question 5

Matching 
Choose the correct answer from the list. Not all the answers will be used.
-_____ and pyruvate can be combined in an ATP dependent reaction that regenerates one of the key intermediates in the citric acid cycle.

Accepted Answer

A) oxaloacetate 
B) malate synthase 
C) malate 
D) malonate 
E) Krebs
F)aconitase
G)succinyl-CoA synthetase
H)α-ketoglutarate
I)carbon dioxide
J)malate dehydrogenase
K)isocitrate
L)succinate dehydrogenase 
A) oxaloacetate 
B) malate synthase 
C) malate 
D) malonate 
E) Krebs
F)aconitase
G)succinyl-CoA synthetase
H)α-ketoglutarate
I)carbon dioxide
J)malate dehydrogenase
K)isocitrate
L)succinate dehydrogenase

Question 6

The figure at right represents an intermediate in the reaction catalyzed by which of the following enzymes?

Accepted Answer

A) enolase 
B) aldolase 
C) pyruvate decarboxylase 
D) glyceraldehyde-3-phosphate dehydrogenase 
E) lactate dehydrogenase 
A) enolase 
B) aldolase 
C) pyruvate decarboxylase 
D) glyceraldehyde-3-phosphate dehydrogenase 
E) lactate dehydrogenase

Question 7

Matching 
Choose the correct answer from the list. Not all the answers will be used.
-______ is the first compound that is oxidized in the citric acid cycle.

Accepted Answer

A) oxaloacetate 
B) malate synthase 
C) malate 
D) malonate 
E) Krebs
F)aconitase
G)succinyl-CoA synthetase
H)α-ketoglutarate
I)carbon dioxide
J)malate dehydrogenase
K)isocitrate
L)succinate dehydrogenase 
A) oxaloacetate 
B) malate synthase 
C) malate 
D) malonate 
E) Krebs
F)aconitase
G)succinyl-CoA synthetase
H)α-ketoglutarate
I)carbon dioxide
J)malate dehydrogenase
K)isocitrate
L)succinate dehydrogenase

Question 8

Which of the following statements correctly and most accurately describes the function of FAD in the pyruvate dehydrogenase enzyme complex?

Accepted Answer

A) NADH passes electrons to FAD to form FADH2. 
B) Lipoamide passes electrons through FADH2, which almost instantly passes them to NAD thus forming NADH. 
C) FADH2 donates electrons to lipoamide thus regenerating FAD. 
D) Lipoamide oxidizes NADH to NAD by passing electrons to FAD. 
E) NAD accepts electrons directly from lipoamide, which has gained them via oxidation of FADH2. 
A) NADH passes electrons to FAD to form FADH2. 
B) Lipoamide passes electrons through FADH2, which almost instantly passes them to NAD thus forming NADH. 
C) FADH2 donates electrons to lipoamide thus regenerating FAD. 
D) Lipoamide oxidizes NADH to NAD by passing electrons to FAD. 
E) NAD accepts electrons directly from lipoamide, which has gained them via oxidation of FADH2.

Question 9

If acetyl-CoA labeled with 14C, as shown in the figure to the right, were used as the substrate for the citric acid cycle, which of the following intermediates would be produced during the first round of the cycle?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 10

Which reaction below produces GTP in the citric acid cycle?

Accepted Answer

A) isocitrate $\rarr$$\alpha$-ketoglutarate 
B) ($\alpha$-ketoglutarate $\rarr$succinyl Co
A)  
C) succinyl CoA $\rarr$ succinate 
D) fumarate $\rarr$ malate 
E) malate $\rarr$ oxaloacetate 
A) isocitrate $\rarr$$\alpha$-ketoglutarate 
B) ($\alpha$-ketoglutarate $\rarr$succinyl Co
A)  
C) succinyl CoA $\rarr$ succinate 
D) fumarate $\rarr$ malate 
E) malate $\rarr$ oxaloacetate

Question 11

Which of the following best describes the importance of the citric acid cycle as a central pathway of metabolism?

Accepted Answer

A) It allows recovery of energy from carbohydrates only. 
B) It allows recovery of energy from fatty acids only. 
C) It allows recovery of energy from amino acids only. 
D) It allows recovery of energy from several metabolic fuels that are broken down to acetyl-CoA. 
E) A and B 
A) It allows recovery of energy from carbohydrates only. 
B) It allows recovery of energy from fatty acids only. 
C) It allows recovery of energy from amino acids only. 
D) It allows recovery of energy from several metabolic fuels that are broken down to acetyl-CoA. 
E) A and B

Question 12

Which of the following amino acid residues facilitates the transfer of a phosphate group in the reaction producing succinate and GTP?

Accepted Answer

A) aspartate 
B) glutamate 
C) histidine 
D) lysine 
E) serine 
A) aspartate 
B) glutamate 
C) histidine 
D) lysine 
E) serine

Question 13

Which of the following enzymes catalyzes a reaction with the pictured compound as an intermediate?

Accepted Answer

A) ($\alpha$-ketoglutarate dehydrogenase) 
B) succinyl-CoA synthetase 
C) succinate dehydrogenase 
D) fumarase 
E) malate dehydrogenase 
A) ($\alpha$-ketoglutarate dehydrogenase) 
B) succinyl-CoA synthetase 
C) succinate dehydrogenase 
D) fumarase 
E) malate dehydrogenase

Question 14

Condensation of ____ with oxaloacetate yield citrate.

Accepted Answer

A) acetyl-CoA 
B) α-ketoglutarate 
C) isocitrate 
D) citrophosphate 
E) oxalosuccinate 
A) acetyl-CoA 
B) α-ketoglutarate 
C) isocitrate 
D) citrophosphate 
E) oxalosuccinate

Question 15

Matching 
Choose the correct answer from the list. Not all the answers will be used.
-The enzyme ______ is part of the glyoxylate cycle that occurs in plants, bacteria, and fungi.

Accepted Answer

A) oxaloacetate 
B) malate synthase 
C) malate 
D) malonate 
E) Krebs
F)aconitase
G)succinyl-CoA synthetase
H)α-ketoglutarate
I)carbon dioxide
J)malate dehydrogenase
K)isocitrate
L)succinate dehydrogenase 
A) oxaloacetate 
B) malate synthase 
C) malate 
D) malonate 
E) Krebs
F)aconitase
G)succinyl-CoA synthetase
H)α-ketoglutarate
I)carbon dioxide
J)malate dehydrogenase
K)isocitrate
L)succinate dehydrogenase

Question 16

Germinating plant seeds can convert acetyl-CoA (obtained from fatty acids stored as oils)into carbohydrates, whereas animals are incapable of converting fatty acids into glucose.This difference is due to the fact that:

Accepted Answer

A) animals have glycogen and don't need to make glucose from fatty acids. 
B) plants use the glyoxylate cycle to convert two acetyl CoA to oxaloacetate, a precursor for gluconeogenesis. 
C) plant seeds use photosynthesis to make sugar. 
D) animals use the citric acid cycle selectively for energy production, whereas plants primarily use glycolysis. 
E) B and D 
A) animals have glycogen and don't need to make glucose from fatty acids. 
B) plants use the glyoxylate cycle to convert two acetyl CoA to oxaloacetate, a precursor for gluconeogenesis. 
C) plant seeds use photosynthesis to make sugar. 
D) animals use the citric acid cycle selectively for energy production, whereas plants primarily use glycolysis. 
E) B and D

Question 17

How many NADH are produced when one acetyl group is oxidized in the citric acid cycle?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) more than 4 
A) 1 
B) 2 
C) 3 
D) 4 
E) more than 4

Question 18

Which of the following steps of the citric acid cycle conserves the energy of a high energy thioester bond?

Accepted Answer

A) the reaction catalyzed by succinate dehydrogenase. 
B) the reaction that produces oxalacetate. 
C) the condensation reaction that produces citrate. 
D) the reaction catalyzed by α-ketoglutarate dehydrogenase. 
E) the conversion of citrate to isocitrate. 
A) the reaction catalyzed by succinate dehydrogenase. 
B) the reaction that produces oxalacetate. 
C) the condensation reaction that produces citrate. 
D) the reaction catalyzed by α-ketoglutarate dehydrogenase. 
E) the conversion of citrate to isocitrate.

Question 19

Which of the following utilizes intermediates of the citric acid cycle?
I.gluconeogenesis
II.amino acid biosynthesis
III.fatty acid oxidation
IV.glycolysis

Accepted Answer

A) I only 
B) II only 
C) I, II, III 
D) I, II 
E) I, IV 
A) I only 
B) II only 
C) I, II, III 
D) I, II 
E) I, IV

Question 20

E2 of the pyruvate dehydrogenase complex contains a lipoyl group that is covalently attached via an amide linkage to a ______ residue on the enzyme?

Accepted Answer

A) tyrosine 
B) serine 
C) lysine 
D) arginine 
E) cysteine 
A) tyrosine 
B) serine 
C) lysine 
D) arginine 
E) cysteine

Exam 17: Citric Acid Cycle

During the oxidation of isocitrate, _____ is decarboxylated to form α\alphaα -ketoglutarate.

Which of the following citric acid cycle intermediates can be converted to aspartate via transamination?

One turn of the citric acid cycle generates

Which of the following causes pyruvate dehydrogenase kinase to catalyze the phosphorylation and inactivation of E1 in the pyruvate dehydrogenase complex?

Matching Choose the correct answer from the list. Not all the answers will be used. -_____ and pyruvate can be combined in an ATP dependent reaction that regenerates one of the key intermediates in the citric acid cycle.

The figure at right represents an intermediate in the reaction catalyzed by which of the following enzymes?

Matching Choose the correct answer from the list. Not all the answers will be used. -______ is the first compound that is oxidized in the citric acid cycle.

Which of the following statements correctly and most accurately describes the function of FAD in the pyruvate dehydrogenase enzyme complex?

If acetyl-CoA labeled with 14C, as shown in the figure to the right, were used as the substrate for the citric acid cycle, which of the following intermediates would be produced during the first round of the cycle?

Which reaction below produces GTP in the citric acid cycle?

Which of the following best describes the importance of the citric acid cycle as a central pathway of metabolism?

Which of the following amino acid residues facilitates the transfer of a phosphate group in the reaction producing succinate and GTP?

Which of the following enzymes catalyzes a reaction with the pictured compound as an intermediate?

Condensation of ____ with oxaloacetate yield citrate.

Matching Choose the correct answer from the list. Not all the answers will be used. -The enzyme ______ is part of the glyoxylate cycle that occurs in plants, bacteria, and fungi.

Germinating plant seeds can convert acetyl-CoA (obtained from fatty acids stored as oils)into carbohydrates, whereas animals are incapable of converting fatty acids into glucose.This difference is due to the fact that:

How many NADH are produced when one acetyl group is oxidized in the citric acid cycle?

Which of the following steps of the citric acid cycle conserves the energy of a high energy thioester bond?

Which of the following utilizes intermediates of the citric acid cycle? I.gluconeogenesis II.amino acid biosynthesis III.fatty acid oxidation IV.glycolysis

E2 of the pyruvate dehydrogenase complex contains a lipoyl group that is covalently attached via an amide linkage to a ______ residue on the enzyme?

Introduction to the Chemistry of Life

Water

Nucleotides, Nucleic Acids, and Genetic Information

Amino Acids

Proteins: Primary Structure

Proteins: Three-Dimensional Structure

Protein Function Part I: Myoglobin and Hemoglobin

Carbohydrates

Lipids and Biological Membranes

Membrane Transport

Enzyme Catalysis

Enzyme Kinetics, Inhibition and Control

Biochemical Signaling

Introduction to Metabolism

Glycogen Metabolism and Gluconeogenesis

Glucose Catabolism

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Mammalian Fuel Metabolism: Integration and Regulation

Nucleotide Metabolism

Nucleic Acid Structure

Dna Replication, Repair and Recombination

Transcription and Rna Processing

Translation

Regulation of Gene Expression

Filters

During the oxidation of isocitrate, _____ is decarboxylated to form $\alpha$ -ketoglutarate.

Which of the following causes pyruvate dehydrogenase kinase to catalyze the phosphorylation and inactivation of E₁ in the pyruvate dehydrogenase complex?

If acetyl-CoA labeled with ¹⁴C, as shown in the figure to the right, were used as the substrate for the citric acid cycle, which of the following intermediates would be produced during the first round of the cycle?

E₂of the pyruvate dehydrogenase complex contains a lipoyl group that is covalently attached via an amide linkage to a ______ residue on the enzyme?