Glycogen

Question 1

What are the 4 main enzymes in glycogen degradation?

Answer 1

Phosphorylase
Mutase
transferase
alpha-1,6-glucosidase

Question 2

What does phosphorylase do in glycogen degradation?

Answer 2

Breaks alpa-1,4-glycosidic bonds of terminal molecules from glycogen to release G1P

Question 3

What does mutase do in glycogen degradation?

Answer 3

Converts G1P to G6P

Question 4

What does transferase do in glycogen degradation?

Answer 4

Moves 3 molecules from branch to main chain to make available for phosphorylase

Question 5

What does alpha-1,6-glucosidase do in glycogen degradation?

Answer 5

Breaks branch bond

Question 6

What is the key regulatory enzyme of glycogen breakdown?

Answer 6

Glycogen phosphorylase

Question 7

What is the active form of phosphorylase?

Answer 7

Phosphorylase a

Question 8

What is the inactive form of phosphorylase?

Answer 8

Phosphorylase b

Question 9

What is the active state of phosphorylase?

Answer 9

R

Question 10

What is the inactive state of phosphorylase?

Answer 10

T

Question 11

What state does phosphorylase a favor?

Answer 11

R

Question 12

What state does phosphorylase b favor?

Answer 12

T

Question 13

Which phosphorylase has a phosphorylated serine residue?

Answer 13

Phosphorylase a

Question 14

What enzyme converts phosphorylase b to phosphorylase a?

Answer 14

Phosphorylase kinase

Question 15

When is phosphorylase kinase maximally active?

Answer 15

When phosphorylated and bound to calcium

Question 16

When is phosphorylation of phosphorylase kinase stimulated?

Answer 16

Signaling cascade of glucagon and epinephrine

Question 17

What is the default phosphorylase in the muscle?

Answer 17

Phosphorylase b in T state

Question 18

What is the default phosphorylase in the liver?

Answer 18

Phosphorylase a in the R state

Question 19

How are phosphorylase a and b interconverted in the muscle?

Answer 19

T to R- 2 AMP
R to T- 2 ATP 2 G6P

Question 20

How are phosphorylase a and b interconverted in the liver?

Answer 20

R to T- 2 glucose

Question 21

What are the main steps of glycogen synthesis?

Answer 21

Glycogenin
UDP-glucose
Glycogen synthase
Branching enzyme

Question 22

What does glycogenin do?

Answer 22

Generates a 10 glucose residue chain for glycogen

Question 23

What is UDP-glucose?

Answer 23

activated carrier of glucose

Question 24

What does glycogen synthase do?

Answer 24

Catalyzes transfer of glucose from UDP-glucose to glycogen

Question 25

What does branching enzyme do?

Answer 25

Cleaves alpa-1,4-linkage and moving 7 residues to synthesize alpha-1,6-linkage

Question 26

What is the key regulatory enzyme of glycogen synthesis?

Answer 26

Glycogen synthase

Question 27

What is the active form of glycogen synthase?

Answer 27

Synthase a

Question 28

What is the inactive form of glycogen synthase?

Answer 28

Synthase b

Question 29

What state does synthase a favor?

Answer 29

R

Question 30

What state does synthase b favor?

Answer 30

T

Question 31

What does phosphorylation do to synthase b?

Answer 31

Inactivates it

Question 32

What converts synthase a to synthase b?

Answer 32

Glycogen synthase kinase

Question 33

What inactivates glycogen synthase kinase?

Answer 33

Insulin through phosphorylation

Question 34

What converts synthase b to synthase a?

Answer 34

PP1

Question 35

What happens to phosphorylase when exercising or fasting?

Answer 35

a form and active, phosphorylated glycogen degradation

Question 36

What happens to glycogen synthase when exercising or fasting?

Answer 36

b form and inactive, phosphorylated

Question 37

What enzymes are active when exercising or fasting?

Answer 37

Protein Kinase A Phosphorylase Kinase Phosphorylase a Glycogen synthase kinase

Question 38

What enzymes are inactive when exercising or fasting?

Answer 38

Glycogen synthase b

Question 39

What happens to phosphorylase when resting or after meal?

Answer 39

b from and inactive, dephosphorylated

Question 40

What happens to glycogen synthase when resting or after meal?

Answer 40

a form and active, dephosphorylated Glycogen synthesis

Question 41

What happens to glycogen synthase when resting or after meal?

Answer 41

a form and active, dephosphorylated Glycogen synthesis

Question 42

What enzymes are inactive when resting or after a meal?

Answer 42

Phosphorylase b Phosphorylase kinase

Question 43

What enzymes are active when resting or after a meal?

Answer 43

Glycogen synthase a

Question 44

Are enzymes phosphorylated or dephosphorylated during glycogen degradation?

Answer 44

Phosphorylated