M6 - Glycogen Metabolism

Question 1

Glycogen Metabolism Location

Answer 1

-Liver, SKM
-Liver GLY = used for hepatic glucose production when fasting
-SKM GLY = used to feed glycolysis, generate ATP for muscle contraction

Question 2

Glycogenesis, Simplified Pathway

Answer 2

• G6P —> Glycogen
• Occurs in cytosol
• Promotes glucose uptake
• Need to branch glycogen

Question 3

Glycogenesis: Glycogen synthase

Answer 3

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

Question 4

Glycogenesis: Branching enzyme

Answer 4

-introduces branch points by creating α(1->6) glycosidic bonds at regular intervals

Question 5

Glycogenolysis, Simplified Pathway

Answer 5

• Glycogen —> G6P
• Occurs in cytosol (and lysosomes)
• Need to debranch glycogen

Question 6

Glycogenolysis: Glycogen phosphorylase

Answer 6

-liberates G1P from linear glycogen chain
-cannot work when it reaches 4 glucose residues from branch point (called the limit dextrin)

Question 7

Glycogenolysis: Debranching enzyme

Answer 7

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

Question 8

Glycogen synthase and glycogen phosphorylase are the _____ enzymes

Answer 8

Regulated

Question 9

Glycogenolysis promotes hepatic glucose ____

Answer 9

Production

Question 10

Glycogenesis promotes hepatic glucose ____

Answer 10

Uptake