Question 1

Why does the liver possess a specific enzyme that can cleave glucose 6-phosphate to form glucose and orthophosphate?

Accepted Answer

The liver controls the blood glucose concentration. Thus, it must be able to remove the phosphate so the glucose can be released from liver cells.

Question 2

Muscle phosphorylase is mostly inactive when:

Accepted Answer

A)  the enzyme is in the b conformation 
B)  in the R state. 
C)  bound to AMP. 
D)  All of the above. 
E)  None of the above. 
A)  the enzyme is in the b conformation 
B)  in the R state. 
C)  bound to AMP. 
D)  All of the above. 
E)  None of the above. D

Question 3

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. C

Question 4

The transferase enzyme shifts a block of ______________ glycosyl units.

Accepted Answer

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

Question 5

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 6

Phosphorylase a and b both 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 7

Which GTP binding protein is activated by epinephrine binding to the adrenergic 7TM receptor?

Accepted Answer

The answer of Which GTP binding protein is activated by...

Question 8

Why must glycogen control be manifested differently in muscle and liver?

Accepted Answer

Because the muscle maintains g

Question 9

How does epinephrine stimulate glycogen breakdown in muscle? (Describe the series of events.)

Accepted Answer

Epinephrine binds to the β-adrenergic re

Question 10

What are some of the advantages of having glycogen as a readily available glucose source?

Accepted Answer

Glycogen is easily broken down, is a rea

Question 11

The key enzyme in glycogen degradation is:

Accepted Answer

A)  glycogen phosphatase. 
B)  glycogen phosphorylase. 
C)  glucose 1-phosphate synthase. 
D)  All of the above. 
E)  None of the above. 
A)  glycogen phosphatase. 
B)  glycogen phosphorylase. 
C)  glucose 1-phosphate synthase. 
D)  All of the above. 
E)  None of the above.

Question 12

Conversion of glucose 1-phosphate to glucose 6-phosphate is carried out by the enzyme:

Accepted Answer

A)  phosphoglucomutase. 
B)  kinase 1-P. 
C)  phosphoglycerate mutase. 
D)  All of the above. 
E)  None of the above. 
A)  phosphoglucomutase. 
B)  kinase 1-P. 
C)  phosphoglycerate mutase. 
D)  All of the above. 
E)  None of the above.

Question 13

Phosphoglucomutase requires the intermediate ______________ for the interconversion of glucose 1-phosphate and glucose 6-phosphate.

Accepted Answer

glucose-1,

Question 14

What is required to remove branches in glycogen?

Accepted Answer

A)  a debranching enzyme 
B)  a transferase enzyme 
C)  a glycosidase enzyme. 
D)  A and C 
E)  All of the above. 
A)  a debranching enzyme 
B)  a transferase enzyme 
C)  a glycosidase enzyme. 
D)  A and C 
E)  All of the above.

Question 15

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 16

What are the three steps in glycogen degradation?

Accepted Answer

The steps are 1) release of gl

Question 17

In the liver, glycogen synthesis and degradation are regulated to maintain levels of ______________ in the blood.

Accepted Answer

The answer of In the liver, glycogen synthesis and degradation...

Question 18

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 19

____________ is the end of glycogen where interconversion between the open and closed conformation of the anomeric carbon is possible

Accepted Answer

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

Question 20

The ____________ enzyme serves as the glucose "sensor" enzyme in liver cells.

Accepted Answer

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

Exam 24: Glycogen Degradation

Why does the liver possess a specific enzyme that can cleave glucose 6-phosphate to form glucose and orthophosphate?

Muscle phosphorylase is mostly inactive when:

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

The transferase enzyme shifts a block of ______________ glycosyl units.

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

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

Which GTP binding protein is activated by epinephrine binding to the adrenergic 7TM receptor?

Why must glycogen control be manifested differently in muscle and liver?

How does epinephrine stimulate glycogen breakdown in muscle? (Describe the series of events.)

What are some of the advantages of having glycogen as a readily available glucose source?

The key enzyme in glycogen degradation is:

Conversion of glucose 1-phosphate to glucose 6-phosphate is carried out by the enzyme:

Phosphoglucomutase requires the intermediate ______________ for the interconversion of glucose 1-phosphate and glucose 6-phosphate.

What is required to remove branches in glycogen?

How is phosphorylase b converted into phosphorylase a?

What are the three steps in glycogen degradation?

In the liver, glycogen synthesis and degradation are regulated to maintain levels of ______________ in the blood.

Two critical hormones that signal for glycogen breakdown are:

____________ is the end of glycogen where interconversion between the open and closed conformation of the anomeric carbon is possible

The ____________ enzyme serves as the glucose "sensor" enzyme in liver cells.

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

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