module 5- glycogen metabolism

Question 1

what enzyme connects glycogen metabolism with PPP, glycolysis & gluconeogenesis?

Answer 1

glucose 6-P

Question 2

T or F: glycogen is a large, branched polymer of glucose

Answer 2

T

Question 3

what is the key regulatory enzyme in glycogen synthesis?

Answer 3

glycogen synthase

Question 4

2 ways glycogen phosphorylase is regulated?

Answer 4

allosterically interactions & reversible phosphorylation

Question 5

what 2 enzymes signal the need for glycogen breakdown?

Answer 5

epinephrine & glucagon

Question 6

glycogen synthase & glycogen degradation are ( ) regulated?

Answer 6

reciprocally

Question 7

what is glycogenin

Answer 7

protein, where glycogen synthase begins

Question 8

T or F: branched structure increases rate of glycogen synthesis & degradation

Answer 8

T

Question 9

what are the 2 linkages responsible for branching

Answer 9

a-1,4 & a-1,6

Question 10

how many ATP are needed per 1 glucose molecule for glycogen synthesis?

Answer 10

2 ATP

Question 11

how many ATP are produced for every 1 glucose 6-P oxidized during glycogen degradation

Answer 11

31

Question 12

what is the % of storage efficiency of glycogen

Answer 12

94%

Question 13

what is glycogen synthesis pathway called

Answer 13

glycogenesis

Question 14

what type of glucose is used in glycogenesis

Answer 14

activated form - called UDP-glucose

Question 15

UDP-glucose function

Answer 15

adds glucose units to glycogen

Question 16

Is UDP-glucose used in glycogen breakdown?

Answer 16

No

Question 17

what is the glycogen degradation pathway called?

Answer 17

glycogenolysis

Question 18

T or F: glucose itself is not the substrate for glycogenesis but UDP-glucose is used as activated precursors

Answer 18

T

Question 19

mutases function

Answer 19

change position of phosphate group

Question 20

glycogen synthesis converts….

Answer 20

glucose -> glycogen

Question 21

glycogen degradation converts…

Answer 21

glycogen -> glucose

Question 22

where is glucose added to the glucose chain & what type of bond does it form?

Answer 22

adds to terminal glucose (C4) to form a-1,4 glycosidic bond

Question 23

how does a glycogen molecule get started?

Answer 23

glycogenin acts as both catalyst & substrate

oligiosacchardie is primer

Question 24

what enzyme catalyzes formation of a-1,6 bond?

Answer 24

the branching enzyme

Question 25

how many residues apart between a-1,6 bonds?

Answer 25

8-12

Question 26

how many glucose units can 1 glycogen have?

Answer 26

30,000

Question 27

what enzyme extends both non-reducing ends followed by more branching?

Answer 27

glycogen synthase

Question 28

what is the key regulatory enzyme in glycogen synthesis

Answer 28

glycogen synthase

Question 29

what enzyme is a strong allosteric activator of glycogen synthase

Answer 29

glucose 6-P

Question 30

phosphorylase A is ( ) form and is ( )

Answer 30

active, phosphorylated

Question 31

phosphorylase B is ( ) form and is ( )

Answer 31

inactive, dephosphorylated

Question 32

main enzyme that degrades glycogen

Answer 32

glycogen phosphorylase

Question 33

glycogen synthase is active in ( ) form and phosphorylase is active in ( )

Answer 33

unphosphorylated, phosphorylated

Question 34

what enzyme interconverts glucose 6-P and glucose 1-P

Answer 34

phosphoglucomutase

Question 35

T or F: glycogen phosphorylase can only cleave a-1,4 bonds

Answer 35

T

Question 36

T or F: the debranching enzyme releases free glucose

Answer 36

T

Question 37

products of the reaction catalyzed by glycogen phosphorylase

Answer 37

glucose 1-P & glycogen molecule that is 1 glucose molecule shorter

Question 38

fates of glucose 6-P in the liver vs muscle

Answer 38

liver- free glucose is produced & enters blood muscle- used by muscles to metabolize energy

Question 39

glycogen storage depletes in ( ) during exercise

Answer 39

1 hour

Question 40

what is glycogen supercompensation

Answer 40

glycogen amounts are doubled

Question 41

what tissue/organ is glycogen phosphorylase b sensitive to allosteric modifiers in?

Answer 41

muscle

Question 42

when is epinephrine secreted? vs when is glucagon secreted?

Answer 42

E-when quick energy burst is needed G- secreted by the pancreas in response to low blood sugar

Question 43

glycogen storage diseases is caused by?

Answer 43

lack of glucose 6-P = unable to release glucose = build up

Question 44

when you eat, glucose levels ( ) which causes insulin ( ) and be stored as glycogen

Answer 44

increase, release

Question 45

T or F: glycogen synthase & glycogen phosphorylase are both regulated by cAMP signalling system

Answer 45

T

Question 46

What enzyme converts glycogen phosphorylase A to B

Answer 46

Phosphatase

Question 47

What enzyme converts glycogen phosphorylase B to A

Answer 47

Kinase

Question 48

6 steps of regulatory cascade

Answer 48

1. Binding of hormone to receptor 2. Adenylate cyclase activated 3. cAMP production increases 4. PKA activation 5. Glycogen phosphorylase is phosphorylase 6. Stimulation of gluconeogenesis

Question 49

Phosphorylase & glycogen synthase become phosphorylated in response to

Answer 49

Glucagon or epinephrine

Question 50

What metabolic pathway does PP1 inhibit?

Answer 50

Glycogenolysis (degradation)

Question 51

Insulin binds to receptor and causes what

Answer 51

Phosphorylation of 2nd messenger