Question 1

The order of prosthetic groups as they act in the three proteins of the PDHpyruvate dehydrogenase) complex is:

Accepted Answer

A)  FAD → thiamine pyrophosphate → NAD+ 
B)  FAD → thiamine pyrophosphate → dihydrolipoamide 
C)  thiamine pyrophosphate → dihydrolipoamide → FAD 
D)  NAD+ → FAD → dihydrolipoamide 
A)  FAD → thiamine pyrophosphate → NAD+ 
B)  FAD → thiamine pyrophosphate → dihydrolipoamide 
C)  thiamine pyrophosphate → dihydrolipoamide → FAD 
D)  NAD+ → FAD → dihydrolipoamide

Question 2

NAD-dependent malate dehydrogenase

Accepted Answer

A)  catalyzes the oxidation of malate to regenerate oxaloacetate. 
B)  catalyzes the conversion of fumarase to malate. 
C)  catalyzes a reaction which results in the formation of an NADH molecule. 
D)  All of the above 
E)  A and C only 
A)  catalyzes the oxidation of malate to regenerate oxaloacetate. 
B)  catalyzes the conversion of fumarase to malate. 
C)  catalyzes a reaction which results in the formation of an NADH molecule. 
D)  All of the above 
E)  A and C only

Question 3

The activity of dihydrolipoamide dehydrogenase E3) is inhibited by a high NADH/NAD+ ratio.

Accepted Answer

A) True 
 B)False

Question 4

Malonate is a competitive inhibitor of the succinate dehydrogenase complex.

Accepted Answer

A) True 
 B)False

Question 5

Which enzyme is the same in both the pyruvate dehydrogenase and α-ketoglutarate complexes?

Accepted Answer

A)  dihydrolipoamide dehydrogenase 
B)  aconitase 
C)  pyruvate decarboxylase 
D)  The two complexes have no components that are similar. 
A)  dihydrolipoamide dehydrogenase 
B)  aconitase 
C)  pyruvate decarboxylase 
D)  The two complexes have no components that are similar.

Question 6

Which of the following inhibits) pyruvate dehydrogenase kinase?

Accepted Answer

A)  pyruvate 
B)  NADH 
C)  acetyl-CoA 
D)  All of the above 
A)  pyruvate 
B)  NADH 
C)  acetyl-CoA 
D)  All of the above

Question 7

Most of the energy released in citric acid cycle reactions is conserved in .

Accepted Answer

A)  GTP 
B)  ATP 
C)  NADH and QH2  
D)  ADP 
A)  GTP 
B)  ATP 
C)  NADH and QH2  
D)  ADP

Question 8

About how many total ATP equivalents are generated by the complete oxidation of one molecule of acetyl CoA?

Accepted Answer

A)  1.5 
B)  2.5 
C)  3 
D)  10 
E)  30 
A)  1.5 
B)  2.5 
C)  3 
D)  10 
E)  30

Question 9

Which process is not implicated in the evolution of the citric acid cycle pathway?

Accepted Answer

A)  gene duplication 
B)  palindromic inversion 
C)  pathway extension 
D)  pathway reversal 
E)  enzyme theft 
A)  gene duplication 
B)  palindromic inversion 
C)  pathway extension 
D)  pathway reversal 
E)  enzyme theft

Question 10

The arrangement of subunits in the PDHpyruvate dehydrogenase) complex ensures that .

Accepted Answer

A)  ATP is formed 
B)  the product of one enzyme is delivered to the next in turn 
C)  the dihydrolipoamide arm can react with NAD+ 
D)  acetyl CoA enters into the series of reactions 
A)  ATP is formed 
B)  the product of one enzyme is delivered to the next in turn 
C)  the dihydrolipoamide arm can react with NAD+ 
D)  acetyl CoA enters into the series of reactions

Question 11

After passing through the citric acid cycle, one mole of pyruvate will result in the formation of moles of carbon dioxide and moles) of ATP or GTP).

Accepted Answer

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

Question 12

Some bacteria and anaerobic eukaryotes not using PDHpyruvate dehydrogenase) form acetyl CoA and CO2 from pyruvate with .

Accepted Answer

A)  PDH modified with methyl groups 
B)  pyruvate:ferredoxin oxidoreductase 
C)  2-oxoacid dehydrogenase 
D)  an isoenzyme of PDH 
A)  PDH modified with methyl groups 
B)  pyruvate:ferredoxin oxidoreductase 
C)  2-oxoacid dehydrogenase 
D)  an isoenzyme of PDH

Question 13

Carbons from acetyl CoA are transferred to the citric acid cycle. Which is the first round of the citric acid cycle that could possibly release a carbon atom originating from this acetyl CoA?

Accepted Answer

A)  first round 
B)  second round 
C)  third round 
D)  fourth round 
A)  first round 
B)  second round 
C)  third round 
D)  fourth round

Question 14

Which of the following are components of the succinate dehydrogenase complex?

Accepted Answer

A)  FAD prosthetic group 
B)  iron-sulfur clusters 
C)  malonate 
D)  All of the above 
E)  A and B only 
A)  FAD prosthetic group 
B)  iron-sulfur clusters 
C)  malonate 
D)  All of the above 
E)  A and B only

Question 15

Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of carbon dioxide?

Accepted Answer

A)  fumarase 
B)  α-ketoglutarate 
C)  succinate 
D)  isocitrate 
A)  fumarase 
B)  α-ketoglutarate 
C)  succinate 
D)  isocitrate

Question 16

Citrate can react asymmetrically in the citric acid cycle because the enzyme aconitase

Accepted Answer

A)  binds citrate asymmetrically. 
B)  binds either form of citrate. 
C)  binds both forms of isocitrate. 
D)  does not distinguish the -CH2COO- group. 
A)  binds citrate asymmetrically. 
B)  binds either form of citrate. 
C)  binds both forms of isocitrate. 
D)  does not distinguish the -CH2COO- group.

Question 17

The citric acid cycle oxidizes pyruvate, and some of the pathway intermediates are starting materials for many biosynthetic pathways. This means the citric acid cycle is .

Accepted Answer

A)  amplifying 
B)  catabolic 
C)  anabolic 
D)  catabolic and anabolic 
A)  amplifying 
B)  catabolic 
C)  anabolic 
D)  catabolic and anabolic

Question 18

The enzyme pyruvate translocase is located .

Accepted Answer

A)  in the cytosol 
B)  in the inner mitochondrial membrane 
C)  in the mitochondrial matrix 
D)  in the endoplasmic reticulum 
A)  in the cytosol 
B)  in the inner mitochondrial membrane 
C)  in the mitochondrial matrix 
D)  in the endoplasmic reticulum

Question 19

Pyruvate passes through the outer mitochondrial membrane by .

Accepted Answer

A)  porin proteins 
B)  passive transport 
C)  pyruvate translocase 
D)  simple diffusion through the lipid bilayer 
A)  porin proteins 
B)  passive transport 
C)  pyruvate translocase 
D)  simple diffusion through the lipid bilayer

Question 20

The citric acid cycle is an anaerobic pathway that occurs in the mitochondria of eukaryotes.

Accepted Answer

A) True 
 B)False

Exam 13: The Citric Acid Cycle

The order of prosthetic groups as they act in the three proteins of the PDHpyruvate dehydrogenase) complex is:

NAD-dependent malate dehydrogenase

The activity of dihydrolipoamide dehydrogenase E3) is inhibited by a high NADH/NAD+ ratio.

Malonate is a competitive inhibitor of the succinate dehydrogenase complex.

Which enzyme is the same in both the pyruvate dehydrogenase and α-ketoglutarate complexes?

Which of the following inhibits) pyruvate dehydrogenase kinase?

Most of the energy released in citric acid cycle reactions is conserved in .

About how many total ATP equivalents are generated by the complete oxidation of one molecule of acetyl CoA?

Which process is not implicated in the evolution of the citric acid cycle pathway?

The arrangement of subunits in the PDHpyruvate dehydrogenase) complex ensures that .

After passing through the citric acid cycle, one mole of pyruvate will result in the formation of moles of carbon dioxide and moles) of ATP or GTP).

Some bacteria and anaerobic eukaryotes not using PDHpyruvate dehydrogenase) form acetyl CoA and CO2 from pyruvate with .

Carbons from acetyl CoA are transferred to the citric acid cycle. Which is the first round of the citric acid cycle that could possibly release a carbon atom originating from this acetyl CoA?

Which of the following are components of the succinate dehydrogenase complex?

Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of carbon dioxide?

Citrate can react asymmetrically in the citric acid cycle because the enzyme aconitase

The citric acid cycle oxidizes pyruvate, and some of the pathway intermediates are starting materials for many biosynthetic pathways. This means the citric acid cycle is .

The enzyme pyruvate translocase is located .

Pyruvate passes through the outer mitochondrial membrane by .

The citric acid cycle is an anaerobic pathway that occurs in the mitochondria of eukaryotes.

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

Filters

The activity of dihydrolipoamide dehydrogenase E₃) is inhibited by a high NADH/NAD⁺ ratio.

Some bacteria and anaerobic eukaryotes not using PDHpyruvate dehydrogenase) form acetyl CoA and CO₂from pyruvate with .