Glycogen Metab

Question 1

Glyocogen location

Answer 1

Liver, SKM
Liver: intial phase of fasting
Muscle: glycolysis and ATP generation for muscle contraction

Question 2

Glycogen synthase

Answer 2

generates linear chain of glucose residues via alpha (1->4) linkages

Question 3

Branching enzyme

Answer 3

Introduces branch points by creating alpha(1->6) glycosidic bonds at regular intervals

Question 4

SKM uses which enzyme to convert glucose to G6P?

Answer 4

Hexokinase

Liver uses both hexokinase and glucokinase

Question 5

Dominant pathway of converting G6P to glucose up to 12-24 hrs following a fast

Answer 5

Hepatic glycogenolysis

Question 6

Dominant pathway of converting G6P to glucose ~18+ hrs following a fast

Answer 6

Hepatic gluconeogenesis

Question 7

Glycogen phosphorylase

Answer 7

Liberates G1P from linear glycogen chain

Cannot work when it reaches 4 glucose residues from branch point (dextrin limit)

Question 8

Debranching enzyme

Answer 8

Relocates the outer 3 glucoses of a limit dextrin to another linear strand
Breaks alpha (1->6) glycosidic bond, liberating a free glucose

Question 9

Glycogen synthase is activated by _____

Answer 9

G6P

Question 10

Glycogen phosphorylase is activated by ____

Answer 10

AMP

Question 11

Glucagon regulation of glycogen

Answer 11

Inc PKA–>:
phosphorylation of glycogen phosphorylase kinase –> phosphorylation & activation of glycogen phosphorylase

phosphorylation & inactivation of glycogen synthase

Question 12

Effect of EPI on glycogenolysis

Answer 12

Stim hep B2-R –> Inc PKA –> Inc glycogenolysis

Question 13

Insulin regulation of glycogen

Answer 13

Inc protein phosphatases that reverse the effects of PKA

Question 14

Glycogen phosphorylase is inhibited by_____

Answer 14

ATP