Question 1

Properly used,glycogen loading by athletes is a safe process.

Accepted Answer

A) True 
 B)False

Question 2

The activity of the enzyme fructose 1,6-bisphosphatase is

Accepted Answer

A)  inhibited by ATP. 
B)  stimulated by AMP. 
C)  inhibited by fructose 2,6-bisphosphate. 
D)  not subject to allosteric control. 
A)  inhibited by ATP. 
B)  stimulated by AMP. 
C)  inhibited by fructose 2,6-bisphosphate. 
D)  not subject to allosteric control.

Question 3

How many ATP equivalents are expended to convert 2 pyruvates to 1 glucose?

Accepted Answer

A)  2 
B)  4 
C)  6 
D)  8 
A)  2 
B)  4 
C)  6 
D)  8

Question 4

Which of the following reactions occur when a single glucose residue is transferred from UDP-glucose to a growing glycogen molecule?

Accepted Answer

A)  UDP is released. 
B)  The glucose can be attached to a #4 carbon atom in the glycogen molecule. 
C)  UDP is released and the glucose is attached to a #4 carbon. 
D)  All of these events can occur when a single glucose residue is added. 
A)  UDP is released. 
B)  The glucose can be attached to a #4 carbon atom in the glycogen molecule. 
C)  UDP is released and the glucose is attached to a #4 carbon. 
D)  All of these events can occur when a single glucose residue is added.

Question 5

It is impossible to reverse any kinase reaction under physiological conditions.

Accepted Answer

A) True 
 B)False

Question 6

In one normal cycle of the pentose phosphate pathway,the enzyme transaldolase is used twice and the enzyme transketolase is used once.

Accepted Answer

A) True 
 B)False

Question 7

Glucose-6-phosphatase activity is found associated with the endoplasmic reticulum.

Accepted Answer

A) True 
 B)False

Question 8

Glycogen phosphorylase and glycogen synthase

Accepted Answer

A)  are not activated simultaneously 
B)  are activated simultaneously under special circumstances 
C)  can be activated simultaneously under any circumstances 
D)  are involved in catalysis of the same process 
A)  are not activated simultaneously 
B)  are activated simultaneously under special circumstances 
C)  can be activated simultaneously under any circumstances 
D)  are involved in catalysis of the same process

Question 9

Which of the following is not true concerning control of pyruvate kinase?

Accepted Answer

A)  The phosphorylated form is less active 
B)  It is inhibited by ATP 
C)  It is activated by fructose 1,6-bisphosphate 
D)  It is inhibited by low blood glucose levels 
E)  All of these 
A)  The phosphorylated form is less active 
B)  It is inhibited by ATP 
C)  It is activated by fructose 1,6-bisphosphate 
D)  It is inhibited by low blood glucose levels 
E)  All of these

Question 10

What kind of reaction is used to release glucose units from glycogen?

Accepted Answer

A)  hydrolysis 
B)  phosphorolysis 
C)  dehydration 
D)  oxidation 
A)  hydrolysis 
B)  phosphorolysis 
C)  dehydration 
D)  oxidation

Question 11

The oxidative reactions of the pentose phosphate pathway

Accepted Answer

A)  produce NADPH rather than NADH. 
B)  require biotin. 
C)  require coenzyme A. 
D)  require thiamine pyrophosphate. 
A)  produce NADPH rather than NADH. 
B)  require biotin. 
C)  require coenzyme A. 
D)  require thiamine pyrophosphate.

Question 12

Generally speaking,the same mechanisms that activate glycogen phosphorylase will turn off glycogen synthase.

Accepted Answer

A) True 
 B)False

Question 13

What is the average chain length of the branches in glycogen?

Accepted Answer

A)  6 glucose residues 
B)  13 glucose residues 
C)  25 glucose residues 
D)  50 glucose residues 
E)  100 glucose residues 
A)  6 glucose residues 
B)  13 glucose residues 
C)  25 glucose residues 
D)  50 glucose residues 
E)  100 glucose residues

Question 14

The vitamin thiamine is important in transferring all of these types of groups,except:

Accepted Answer

A)  2-carbon sugar fragments 
B)  3-carbon sugar fragments 
C)  4-carbon sugar fragments 
D)  Sugar fragments which contain a carbonyl group (C=O). 
E)  Thiamine can transfer all of these types of groups. 
A)  2-carbon sugar fragments 
B)  3-carbon sugar fragments 
C)  4-carbon sugar fragments 
D)  Sugar fragments which contain a carbonyl group (C=O). 
E)  Thiamine can transfer all of these types of groups.

Question 15

Which of the following best describes the function of debranching enzyme?

Accepted Answer

A)  It simply cleaves a(1 6) bonds in glycogen via phosphorolysis. 
B)  It transfers a set of three glucose residues from a limit branch and then cleaves the a(1 6) bond via phosphorylsis. 
C)  It simply cleaves a(1 6) bonds in glycogen via hydrolysis. 
D)  It transfers a set of three glucose residues from a limit branch and then cleaves the a(1 6) bond via hydrolysis. 
A)  It simply cleaves a(1 6) bonds in glycogen via phosphorolysis. 
B)  It transfers a set of three glucose residues from a limit branch and then cleaves the a(1 6) bond via phosphorylsis. 
C)  It simply cleaves a(1 6) bonds in glycogen via hydrolysis. 
D)  It transfers a set of three glucose residues from a limit branch and then cleaves the a(1 6) bond via hydrolysis.

Question 16

In general,opposing pathways,such as glycolysis and gluconeogenesis are not exact reversals of each other.

Accepted Answer

A) True 
 B)False

Question 17

Glycogen loading is particularly advantageous for providing energy for long distance athletic events,such as running the marathon.

Accepted Answer

A) True 
 B)False

Question 18

During the pentose phosphate pathway (glucose-6-P ribose-5-P),is there a net oxidation of the substrate carbon atoms?

Accepted Answer

A)  Yes. 
B)  No. 
C)  It depends on whether the process is under aerobic or anaerobic conditions. 
D)  It depends on the species doing the process. 
E)  It depends on whether the glucose goes through the oxidative part of the pathway or not. 
A)  Yes. 
B)  No. 
C)  It depends on whether the process is under aerobic or anaerobic conditions. 
D)  It depends on the species doing the process. 
E)  It depends on whether the glucose goes through the oxidative part of the pathway or not.

Question 19

There is as much energy used to add a phosphate group by means of phosphorolysis,as the energy required adding a phosphate using ATP.

Accepted Answer

A) True 
 B)False

Question 20

Which of the following is not a control mechanism for glycogen phosphorylase?

Accepted Answer

A)  Covalent modification. 
B)  Inhibition by glucose. 
C)  Subunit association and dissociation. 
D)  Allosteric stimulation by AMP. 
E)  All of these mechanisms regulate the activity of glycogen synthase. 
A)  Covalent modification. 
B)  Inhibition by glucose. 
C)  Subunit association and dissociation. 
D)  Allosteric stimulation by AMP. 
E)  All of these mechanisms regulate the activity of glycogen synthase.

Exam 18: Storage Mechanisms and Control in Carbohydrate Metabolism

Properly used,glycogen loading by athletes is a safe process.

The activity of the enzyme fructose 1,6-bisphosphatase is

How many ATP equivalents are expended to convert 2 pyruvates to 1 glucose?

Which of the following reactions occur when a single glucose residue is transferred from UDP-glucose to a growing glycogen molecule?

It is impossible to reverse any kinase reaction under physiological conditions.

In one normal cycle of the pentose phosphate pathway,the enzyme transaldolase is used twice and the enzyme transketolase is used once.

Glucose-6-phosphatase activity is found associated with the endoplasmic reticulum.

Glycogen phosphorylase and glycogen synthase

Which of the following is not true concerning control of pyruvate kinase?

What kind of reaction is used to release glucose units from glycogen?

The oxidative reactions of the pentose phosphate pathway

Generally speaking,the same mechanisms that activate glycogen phosphorylase will turn off glycogen synthase.

What is the average chain length of the branches in glycogen?

The vitamin thiamine is important in transferring all of these types of groups,except:

Which of the following best describes the function of debranching enzyme?

In general,opposing pathways,such as glycolysis and gluconeogenesis are not exact reversals of each other.

Glycogen loading is particularly advantageous for providing energy for long distance athletic events,such as running the marathon.

During the pentose phosphate pathway (glucose-6-P ribose-5-P),is there a net oxidation of the substrate carbon atoms?

There is as much energy used to add a phosphate group by means of phosphorolysis,as the energy required adding a phosphate using ATP.

Which of the following is not a control mechanism for glycogen phosphorylase?

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

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism: Cellular Signaling

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