Glycogen metabolism

Question 1

Glycogenesis rxns + enzymes

Answer 1

G > G6P > G1P > UDPG > Glycogen
1: HK
2: PGM
3: UDPG pyrophosphorylase
4: Glycogen synthase + branching enzyme

Question 2

Glycogen primer

Answer 2

Glycogenin

Question 3

T/F: G1P attacks the y P of UTP > UDPG

Answer 3

False. It attacks the @P

Question 4

Debranching enzyme

Answer 4

Bifunctional:
- Glucan transferase(transfer 3 glu to another branch)
- @-1,6 glycosidase(releases free glu from branching point)

Question 5

When phosphorylated:
- Glycogen synthase
- Glycogen phosphorylase

Answer 5

• Inactive
• Active

Question 6

PKA does 2 things:

Answer 6

1- phosphorylates phosphorylase b > pa(active)…phosphorylates glycogen pb > glycogen pa(active)…glycogenolysis
2- phosphorylates PPI(active)…glycogenolysis

Question 7

PP-1 active vs inactive

Answer 7

active when bound to glycogen…caused by insulin
inactive when released alone or by PPI

Question 8

T/F: Epinephrine and insulin oppose in muscle

Answer 8

True

Question 9

Glycogen storage diseases:
VG

Answer 9

• Type 1
• G-6-phosphatase deficiency(only liver)
• Hypoglycemic, ketotic, hyperuricemic
• No fast, no sugar, more slow carbs

Question 10

McArdle’s

Answer 10

• Type 5
• Muscle glycogen phosphorylase deficiency
• Cramps, fatigue
• No increase in lactate after exercise

Question 11

Pompe’s

Answer 11

• Type 2
• @glucosidase deficiency
• Glycogen accumulate in lysosomes > heart failure
• No hypoglycemia(G6PASE active)

Question 11

Cori’s

Answer 11

• Type 3
• Debranching enzyme deficiency
• No lactic acidosis
• Milder hypoglycemia
• gluconeogenesis intact