Chapter 24 & 25

Question 1

glycogen

Answer 1

highly branched homopolymers of glucose present in all tissues

Question 2

largest stores of glycogen are in…

Answer 2

the liver and muscle

Question 3

Liver breaks down glucose and releases it to..

Answer 3

blood to provide energy for brain and RBC

Question 4

muscle glycogen stores are mobilized to provide energy for…

Answer 4

muscle contraction

Question 5

glycogen is synthesized and degraded by…

Answer 5

different pathways

Question 6

glycogenolysis

Answer 6

degradation of glycogen

Question 7

glycogenesis

Answer 7

biosynthesis of glycogen

Question 8

UDP-GLucose

Answer 8

an activated form of glucose

Question 9

phosphoglucomutase

Answer 9

reversible rex between glucose 6-P and glucose 1-P

Question 10

glucose 1-P is converted to UDP-glucose by..

Answer 10

UDP glucose pyrophosphorylase

Question 11

glycogen synthase

Answer 11

transfers a glucose moiety from UDP-glucose to C-4 terminal of glycogen to form an a-1,4-glycosidic bond

Question 12

Why is branching important?

Answer 12

increases rate of glycogen synthesis and degradation by increasing solubility of glycogen, creating a large number of terminal residues

Question 13

terminal residues

Answer 13

sites of action of glycogen phosphorylase and synthase

Question 14

a-1,4 linkage to a-1,6 linkage

Answer 14

• UDP-glucose + glycogen synthase

- branching enzyme

Question 15

initiation of glycogenesis

Answer 15

• self catalyzed attachment of glucose residue to Tyr 194 OH group of glycogenin
• extension of the gluten chain up to 8 glucose residues, forming the primer for initiation of glycogen synthesis
• glycogen synthase further extends chain

Question 16

glycogen phosphorylase

Answer 16

degrades glycogen from nonreducing ends of glycogen molecule; yields glucose 1-P

Question 17

glucose 1-P is converted to glucose 6-P by…

Answer 17

phosphoglucomutase

Question 18

glycogen phosphorylase can only cleave..

Answer 18

near branch points and only at a-1,4-glycosidic bonds

Question 19

How does glycogen phosphorylase degrade the remainder of the glycogen molecule?

Answer 19

transferase and a-1,6-glucosidase react to form a linear chain with all a-1,4 linkages suitable for further cleavage by phosphorylase

Question 20

glucose 6-phosphatase is present in…

Answer 20

liver and absent in most other tissues

Question 21

glucose 6-phosphatase generates…

Answer 21

free glucose from glucose 6-phosphate in liver

Question 22

difference between active and inactive glycogen phosphorylase

Answer 22

active has a phosphate group

Question 23

phosphorylase phosphatase

Answer 23

converts active GP to inactive GP by removing phosphate group from serine residue (release if Pi)

Question 24

phosphorylase kinase

Answer 24

converts inactive GP to active by adding a phosphate group to serine residue (IN PRESENCE OF ATP)

Question 25

In muscle, what inhibits GP

Answer 25

ATP and G6-P

Question 26

in muscle, what activates GP?

Answer 26

AMP

Question 27

in the liver, what inhibits GP?

Answer 27

glucose

Question 28

difference between active and inactive glycogen synthase?

Answer 28

inactive form has a phosphate group

Question 29

protein kinases (GSK-3)

Answer 29

inactivates active form of GS with addition of phosphate group in presence of ATP

Question 30

protein phosphatases (PP1)

Answer 30

activates inactive form of GS by removing phosphate group and releasing Pi

Question 31

in both muscle and liver, what activates GP “b”?

Answer 31

glucose 6-P

Question 32

glucagon is produced in..

Answer 32

in pancrease

Question 33

epinephrine is produced in ..

Answer 33

adrenal glands

Question 34

2 WAYS INSULIN ACTIVATES GLYCOGEN SYNTHESIS?

Answer 34

• INACTIVATES GSK-3

- ACTIVATES PP1