Question 1

Why can't the glucose 1-phosphate diffuse out of the cell?

Accepted Answer

There is no membrane transporter for glucose 1-phosphate and the negative charge traps it inside so it cannot diffuse through the cell membrane.

Question 2

What path, in addition to the cAMP-induced signal transduction, is used in the liver to stimulate glycogen breakdown by epinephrine?

Accepted Answer

In the liver, epinephrine also binds to a 7TM ɑ-adrenergic receptor, which activates phospholipase C and the phosphoinositide cascade. This causes calcium ions to be released, which bind to calmodulin, and further stimulates phosphorylase kinase and glycogen breakdown.

Question 3

What are the three steps in glycogen degradation?

Accepted Answer

The steps are 1) release of glucose 1-phosphate from glycogen, 2) remodeling of glycogen substrate, and 3) formation of glucose 6-phosphate from glucose 1-phosphate.

Question 4

In order to degrade branches in glycogen, two enzymes are required: a transferase and ______________.

Accepted Answer

The answer of In order to degrade branches in glycogen,...

Question 5

What physiological conditions render phosphorylase b less active?

Accepted Answer

A)  high ATP, high AMP, and glucose 6-phosphate levels 
B)  high ATP and low calcium ion levels 
C)  high ATP and high glucose 6-phosphate levels 
D)  All of the above. 
E)  None of the above. 
A)  high ATP, high AMP, and glucose 6-phosphate levels 
B)  high ATP and low calcium ion levels 
C)  high ATP and high glucose 6-phosphate levels 
D)  All of the above. 
E)  None of the above.

Question 6

How is phosphorylase b converted into phosphorylase a?

Accepted Answer

A)  through the addition of a phosphate to a serine residue 
B)  through dimerization, which forms the active-site pocket 
C)  through cleavage of 10 amino acids from the N-terminal end of the protein 
D)  All of the above. 
E)  None of the above. 
A)  through the addition of a phosphate to a serine residue 
B)  through dimerization, which forms the active-site pocket 
C)  through cleavage of 10 amino acids from the N-terminal end of the protein 
D)  All of the above. 
E)  None of the above.

Question 7

Choose the correct answer from the list below. Not all of the answers will be used.
-The process by which a bond is cleaved by the addition of orthophosphate is ____________.

Accepted Answer

A) reducing 
B) α-1,6-glycosidic 
C) phosphorylase kinase 
D) α-1,4-glycoside 
E) nonreducing
F)phosphorylase a
G)glucose 6-phosphatase
H)UTP-glucose
I)calmodulin
J)phosphorolysis
K)epinephrine
L)glucagon 
A) reducing 
B) α-1,6-glycosidic 
C) phosphorylase kinase 
D) α-1,4-glycoside 
E) nonreducing
F)phosphorylase a
G)glucose 6-phosphatase
H)UTP-glucose
I)calmodulin
J)phosphorolysis
K)epinephrine
L)glucagon

Question 8

Which liver enzyme is deficient in Hers disease?

Accepted Answer

A)  phosphorylase 
B)  transferase 
C)  glucosidase 
D)  phosphoglucomutase 
E)  None of the above. 
A)  phosphorylase 
B)  transferase 
C)  glucosidase 
D)  phosphoglucomutase 
E)  None of the above.

Question 9

One mechanism for turning off glycogen degradation involves the removal of a phosphate group from glycogen phorphorylase by the enzyme ____________.

Accepted Answer

protein ph

Question 10

Choose the correct answer from the list below. Not all of the answers will be used.
-____________: Most of the glucose residues in glycogen are linked by this type of bond.

Accepted Answer

A) reducing 
B) α-1,6-glycosidic 
C) phosphorylase kinase 
D) α-1,4-glycoside 
E) nonreducing
F)phosphorylase a
G)glucose 6-phosphatase
H)UTP-glucose
I)calmodulin
J)phosphorolysis
K)epinephrine
L)glucagon 
A) reducing 
B) α-1,6-glycosidic 
C) phosphorylase kinase 
D) α-1,4-glycoside 
E) nonreducing
F)phosphorylase a
G)glucose 6-phosphatase
H)UTP-glucose
I)calmodulin
J)phosphorolysis
K)epinephrine
L)glucagon

Question 11

In skeletal muscle, the binding of ______________ stabilizes phosphorylation b into the active form.

Accepted Answer

The answer of In skeletal muscle, the binding of ______________...

Question 12

Choose the correct answer from the list below. Not all of the answers will be used.
-The type of bond that is located at the branch points in glycogen is ____________.

Accepted Answer

A) reducing 
B) α-1,6-glycosidic 
C) phosphorylase kinase 
D) α-1,4-glycoside 
E) nonreducing
F)phosphorylase a
G)glucose 6-phosphatase
H)UTP-glucose
I)calmodulin
J)phosphorolysis
K)epinephrine
L)glucagon 
A) reducing 
B) α-1,6-glycosidic 
C) phosphorylase kinase 
D) α-1,4-glycoside 
E) nonreducing
F)phosphorylase a
G)glucose 6-phosphatase
H)UTP-glucose
I)calmodulin
J)phosphorolysis
K)epinephrine
L)glucagon

Question 13

Why is the T state of glycogen phosphorylase less active?

Accepted Answer

A)  The adjacent amino acids are not phosphorylated; thus the catalysis cannot be carried out. 
B)  The active site is partially blocked. 
C)  ATP cannot be bound by the T state. 
D)  All of the above. 
E)  None of the above. 
A)  The adjacent amino acids are not phosphorylated; thus the catalysis cannot be carried out. 
B)  The active site is partially blocked. 
C)  ATP cannot be bound by the T state. 
D)  All of the above. 
E)  None of the above.

Question 14

Which molecule(s) must be excluded from the active site of glycogen phosphorylase?

Accepted Answer

A)  glucose 
B)  glucose 1-phosphate 
C)  water 
D)  All of the above. 
E)  None of the above. 
A)  glucose 
B)  glucose 1-phosphate 
C)  water 
D)  All of the above. 
E)  None of the above.

Question 15

The hydrolysis catalyzed by α-1,6-glucosidase releases a(n) ______________ molecule.

Accepted Answer

The answer of The hydrolysis catalyzed by α-1,6-glucosidase releases a(n)...

Question 16

What are the two regulatory controls for phosphorylase kinase?

Accepted Answer

Phosphorylase kinase is activa

Question 17

Two critical hormones that signal for glycogen breakdown are:

Accepted Answer

A)  insulin and epinephrine. 
B)  glucagon and epinephrine. 
C)  glucagon and insulin. 
D)  All of the above. 
E)  None of the above. 
A)  insulin and epinephrine. 
B)  glucagon and epinephrine. 
C)  glucagon and insulin. 
D)  All of the above. 
E)  None of the above.

Question 18

Both phosphorylase a and b exist in equilibrium between R and T states. Which are the most active and least active combinations?

Accepted Answer

The most active is phosphoryla

Question 19

Why is the formation of glucose 1-phosphate advantageous?

Accepted Answer

It is advantageous because the

Question 20

The transferase enzyme shifts a block of ______________ glycosyl units.

Accepted Answer

The answer of The transferase enzyme shifts a block of...

Exam 24: Glycogen Degradation

Why can't the glucose 1-phosphate diffuse out of the cell?

What path, in addition to the cAMP-induced signal transduction, is used in the liver to stimulate glycogen breakdown by epinephrine?

What are the three steps in glycogen degradation?

In order to degrade branches in glycogen, two enzymes are required: a transferase and ______________.

What physiological conditions render phosphorylase b less active?

How is phosphorylase b converted into phosphorylase a?

Choose the correct answer from the list below. Not all of the answers will be used. -The process by which a bond is cleaved by the addition of orthophosphate is ____________.

Which liver enzyme is deficient in Hers disease?

One mechanism for turning off glycogen degradation involves the removal of a phosphate group from glycogen phorphorylase by the enzyme ____________.

Choose the correct answer from the list below. Not all of the answers will be used. -____________: Most of the glucose residues in glycogen are linked by this type of bond.

In skeletal muscle, the binding of ______________ stabilizes phosphorylation b into the active form.

Choose the correct answer from the list below. Not all of the answers will be used. -The type of bond that is located at the branch points in glycogen is ____________.

Why is the T state of glycogen phosphorylase less active?

Which molecule(s) must be excluded from the active site of glycogen phosphorylase?

The hydrolysis catalyzed by α-1,6-glucosidase releases a(n) ______________ molecule.

What are the two regulatory controls for phosphorylase kinase?

Two critical hormones that signal for glycogen breakdown are:

Both phosphorylase a and b exist in equilibrium between R and T states. Which are the most active and least active combinations?

Why is the formation of glucose 1-phosphate advantageous?

The transferase enzyme shifts a block of ______________ glycosyl units.

Biochemistry and the Unity of Life

Water, Weak Bonds, and the Generation of Order Out of Chaos

Amino Acids

Protein Three-Dimensional Structure

Techniques in Protein Biochemistry

Basic Concepts of Enzyme Action

Kinetics and Regulation

Mechanisms and Inhibitors

Hemoglobin: an Allosteric Protein

Carbohydrates

Lipids

Membrane Structure and Function

Signal Transduction Pathways

Digestion: Turning a Meal Into Cellular Biochemicals

Metabolism: Basic Concepts and Design

Glycolysis

Gluconeogenesis

Preparation for the Cycle

Harvesting Electrons From the Cycle

The Electron Transport Chain

The Proton-Motive Force

The Light Reactions

The Calvin Cycle

Glycogen Synthesis

The Pentose Phosphate Pathway

Fatty Acid Degredation

Fatty Acid Synthesis

Lipid Synthesis

Amino Acid Degradation and the Urea Cycle

Amino Acids Synthesis

Nucleotide Metabolism

The Structure of Informational Macromolecules: Dna and Rna

DNA Replication

DNA Repair and Recombination

RNA Synthesis and Regulation in Prokaryotes

Gene Expression in Eukaryotes

RNA Processing in Eukaryotes

The Genetic Code

The Mechanism of Protein Synthesis

Recombinant DNA Techniques

Filters