Glycogen Metabolism

Question 1

Glycogen synthesis takes place in the___ of the liver and skeletal muscle.

Answer 1

Cytosol

Question 2

Where are the glucosyl units added to elongate glycogen chain, and what bond does it form?

Answer 2

Nonreducing, a-1,4 glycosidic bond

Question 3

What is the primer for the initiation of glycogen synthesis?

Answer 3

Glycogenin

Question 4

Glycogen synthase creates only ____-linkages

Answer 4

a-1,4-linkage

Question 5

What are long unbranched chains called?

Answer 5

a-amylose

Question 6

Branching to form glycogen is accomplished by the _____ enzyme

Answer 6

Branching enzyme

Question 7

Branching enzyme is also called?

Answer 7

Glycosyl (4,6) transferase

Question 8

Elongation forms what bond?

Answer 8

a-1,4 bonds

Question 9

Branching form what bond?

Answer 9

a-1,6 bonds

Question 10

Each transferred segment must come from a chain of at least __ residues long and the new branch point must be at least __ residues away from other branch points.

Answer 10

11, 4

Question 11

Branching is important because it _____ the solubility of glycogen.

Answer 11

Increases

Question 12

Glycogen phosphorylase (breakdown) catalyzes glycogen phosphorolysis to yield?

Answer 12

Glucose-1-phosphate (G1P)

Question 13

Pyrodoxal phophate (PLP) is an essential _____ for glycogen phosphorylase.

Answer 13

Coenzyme

Question 14

Glycogen phosphorylase will only cleave a-1,4 glycosidic bonds between the glucosyl residues at the _____ ends of the glycogen chain.

Answer 14

Nonreducing

Question 15

Glycogen phosphorylase will only release a glucose unit that is at least ___units from a branching point.

Answer 15

5

Question 16

The remaining 4 glucosyl units around each branch point are called ___ because glycogen phosphorylase cannot degrade these any further.

Answer 16

Limt dextrins

Question 17

What are the 2 glycogen debranching enzyme?

Answer 17

Glycosyl (4:4) transferase, amylo-a-(1,6)-glucosidase (releasing free glucose)

Question 18

Branching enzyme, cirrhosis of liver, death before age 2 is what disease?

Answer 18

Andersen’s

Question 19

Glycogen phosphorylase defect, limited ability to perform strenuous exercise because of painful muscle cramps. What disease is this?

Answer 19

McArdle

Question 20

Glycose 6-phosphatase defect, severe hypoglycemia, massive liver is what disease?

Answer 20

Von Gierke

Question 21

The level of ___during exercise increases much more in a patient with McArdle’s disease

Answer 21

ADP

Question 22

Fanconi-Bickel’s disease affects the production of ___ transports.

Answer 22

GLUT2