W3-2: Glycogen metabolism

Question 1

Linear glycogen is bonded at which glucose carbons?

Answer 1

1 (phosporylated) –> 4

Question 2

Branched glycogen is bonded at which glucose carbons?

Answer 2

1 phosphorylated –> 6

Question 3

Glc activation for glycogen synthesis

Answer 3

Question 4

Glycogen synthesis occurs in which direction?

Answer 4

1’ to 4’

Question 5

Branching enzyme name

Answer 5

glycosyl 4–>6 transferase

Question 6

About how many Glc molecules can be added at a branch point?

Answer 6

~11

Question 7

What is the benefit of having so many branch points?

Answer 7

more loose ends are available to be cleaved off the glycogen molecule

and

increases solubility (more –OH groups)

Question 8

Enzyme that cleaves Glc off glycogen

Answer 8

glycogen phosphorylase

Question 9

Two debranching enzymes

Answer 9

4:6 transferase

**moves all but one sugar**

α-1,6-glucosidase

**frees last Glc**

Question 10

Two enzymes that control glycogen synthesis/breakdown and regulation

Answer 10

Question 11

Glucagon and Epi action: fasting hepatocyte

Answer 11

Question 12

Insulin action: fed hepatocyte

Answer 12

PHOSPHORYLASE

Question 13

Epi action: fasting skeletal muscle

Answer 13

PHOSPHORYLASE

Question 14

Insulin action: fed skeletal muscle

Answer 14

Question 15

GSD 0

Answer 15

Glycogen synthase deficiency

Question 16

GSD I (van Gierke disease)

Answer 16

Glucose-6-phosphatase deficiency

(cannot remove Glc from liver)

Question 17

GSD III (Cori disease)

Answer 17

1,6-glucosidase activity deficincy

(cannot remove single sugar)

Question 18

GSD IV

Answer 18

4:6-transferase defiency

fatal

Question 19

GSD V (McArdle disease)

Answer 19

Muscle glycogen phosphorylase deficiency

–>exercise intolerance