Question 1

In eukaryotes the enzymes of the citric acid cycle are found in the ________.

Accepted Answer

A) cytosol 
B) mitochondria 
C) nucleus 
D) endoplasmic reticulum 
A) cytosol 
B) mitochondria 
C) nucleus 
D) endoplasmic reticulum

Question 2

Malonate is a competitive inhibitor of the succinate dehydrogenase complex.

Accepted Answer

A) True 
 B)False

Question 3

During catalysis,succinyl CoA synthetase generates

Accepted Answer

A) an energy deficient,unstable phosphoenzyme intermediate. 
B) an energy rich,unstable phosphoenzyme intermediate. 
C) an energy rich,stable phosphoenzyme intermediate. 
D) All of the above. 
A) an energy deficient,unstable phosphoenzyme intermediate. 
B) an energy rich,unstable phosphoenzyme intermediate. 
C) an energy rich,stable phosphoenzyme intermediate. 
D) All of the above.

Question 4

Which of the following is/are true statements about the succinate dehydrogenase reactions?

Accepted Answer

A) It is stereospecific. 
B) Only the cis-isomer of the product is formed. 
C) It is not stereospecific. 
D) Both B and C. 
A) It is stereospecific. 
B) Only the cis-isomer of the product is formed. 
C) It is not stereospecific. 
D) Both B and C.

Question 5

Which statement is true about lactate dehydrogenase and malate dehydrogenase?

Accepted Answer

A) Both enzymes are highly specific for their own substrates. 
B) A single amino acid change can convert lactate dehydrogenase to a malate dehydrogenase. 
C) The naturally occurring enzymes do not have much sequence similarity,but do have closely related three-dimensional structures. 
D) All of the above. 
A) Both enzymes are highly specific for their own substrates. 
B) A single amino acid change can convert lactate dehydrogenase to a malate dehydrogenase. 
C) The naturally occurring enzymes do not have much sequence similarity,but do have closely related three-dimensional structures. 
D) All of the above.

Question 6

Which statement is false about the glyoxylate cycle?

Accepted Answer

A) In mammals the glyoxylate cycle is used to replenish citric acid cycle intermediates. 
B) It is an anabolic alternative for the metabolism of acetyl CoA. 
C) It can be regarded as a shunt in the citric acid cycle. 
D) In eukaryotes,metabolites must be transferred from the mitochondria to the cytosol to be used in the glyoxylate cycle. 
A) In mammals the glyoxylate cycle is used to replenish citric acid cycle intermediates. 
B) It is an anabolic alternative for the metabolism of acetyl CoA. 
C) It can be regarded as a shunt in the citric acid cycle. 
D) In eukaryotes,metabolites must be transferred from the mitochondria to the cytosol to be used in the glyoxylate cycle.

Question 7

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 8

Which is not produced by the citric acid cycle?

Accepted Answer

A) NADH 
B) FMN 
C) CO2 
D) QH2 
A) NADH 
B) FMN 
C) CO2 
D) QH2

Question 9

The overall goal of the citric acid cycle is to oxidize acetate,form reduced coenzymes,and produce ATP.

Accepted Answer

A) True 
 B)False

Question 10

The citric acid cycle can be viewed as a multi-step catalyst simply because it returns to its original state after each round of reactions.

Accepted Answer

A) True 
 B)False

Question 11

Dehydrogenases that act on α-ketoglutarate (in the citric acid cycle)and on branch chain alpha-keto acids (in amino acid metabolism)closely resemble pyruvate dehydrogenase in structure and function.

Accepted Answer

A) True 
 B)False

Question 12

Please match the following reactions to their respective energy yielding products.
Please note that a product may be used once,more than once,or not at all as an answer.
-α-ketoglutarate dehydrogenase complex

Accepted Answer

A) NADH 
B) QH² 
C) GTP or ATP 
A) NADH 
B) QH² 
C) GTP or ATP

Question 13

The recycling of NAD allows glycolysis to continue in the absence of oxygen.

Accepted Answer

A) True 
 B)False

Question 14

Some bacteria and anaerobic eukaryotes not using PDH(pyruvate 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 15

The citric acid cycle produces a nucleotide triphosphate directly by substrate level phosphorylation.

Accepted Answer

A) True 
 B)False

Question 16

A deficiency in thiamine causes the disease beriberi.Which might you expect to have a higher than normal blood concentration in an individual with this condition?

Accepted Answer

A) Isocitrate. 
B) Pyruvate. 
C) Oxaloacetate. 
D) Acetyl CoA. 
A) Isocitrate. 
B) Pyruvate. 
C) Oxaloacetate. 
D) Acetyl CoA.

Question 17

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 18

The step at which acetyl CoA enters the citric acid cycle is classified as a ________ reaction.

Accepted Answer

A) condensation 
B) substrate-level phosphorylation 
C) decarboxylation 
D) dehydrogenation 
A) condensation 
B) substrate-level phosphorylation 
C) decarboxylation 
D) dehydrogenation

Question 19

When energy-rich acetyl CoA is oxidized to carbon dioxide,eight electrons are released.Most often,electrons are released in such reactions because

Accepted Answer

A) double bonds formed in CO2 share electron pairs. 
B) there are more electrons in the reactants than in the products. 
C) water is not available in the reaction. 
D) an electron acceptor is linked to the reaction. 
A) double bonds formed in CO2 share electron pairs. 
B) there are more electrons in the reactants than in the products. 
C) water is not available in the reaction. 
D) an electron acceptor is linked to the reaction.

Question 20

Which is not a component of the pyruvate dehydrogenase complex?

Accepted Answer

A) Dihydrolipoamide dehydrogenase. 
B) Isocitrate dehydrogenase. 
C) Pyruvate dehydrogenase. 
D) Dihydrolipoamide acetyltransferase. 
A) Dihydrolipoamide dehydrogenase. 
B) Isocitrate dehydrogenase. 
C) Pyruvate dehydrogenase. 
D) Dihydrolipoamide acetyltransferase.

Exam 13: The Citric Acid Cycle

In eukaryotes the enzymes of the citric acid cycle are found in the ________.

Malonate is a competitive inhibitor of the succinate dehydrogenase complex.

During catalysis,succinyl CoA synthetase generates

Which of the following is/are true statements about the succinate dehydrogenase reactions?

Which statement is true about lactate dehydrogenase and malate dehydrogenase?

Which statement is false about the glyoxylate cycle?

The enzyme pyruvate translocase is located ________.

Which is not produced by the citric acid cycle?

The overall goal of the citric acid cycle is to oxidize acetate,form reduced coenzymes,and produce ATP.

The citric acid cycle can be viewed as a multi-step catalyst simply because it returns to its original state after each round of reactions.

Dehydrogenases that act on α-ketoglutarate (in the citric acid cycle)and on branch chain alpha-keto acids (in amino acid metabolism)closely resemble pyruvate dehydrogenase in structure and function.

Please match the following reactions to their respective energy yielding products. Please note that a product may be used once,more than once,or not at all as an answer. -α-ketoglutarate dehydrogenase complex

The recycling of NAD allows glycolysis to continue in the absence of oxygen.

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

The citric acid cycle produces a nucleotide triphosphate directly by substrate level phosphorylation.

A deficiency in thiamine causes the disease beriberi.Which might you expect to have a higher than normal blood concentration in an individual with this condition?

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?

The step at which acetyl CoA enters the citric acid cycle is classified as a ________ reaction.

When energy-rich acetyl CoA is oxidized to carbon dioxide,eight electrons are released.Most often,electrons are released in such reactions because

Which is not a component of the pyruvate dehydrogenase complex?

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 Atp Synthesis

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

DNA Replication, repair, and Recombination

Transcription and RNA Processing

Protein Synthesis

Filters

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