1.2 Glycogenesis

Question 1

Give the location of glycogenesis

Answer 1

• Hepatocytes
• Muscle cells
• Kidney
• Parenchymal cells

Cell cytoplasm

Question 2

Give the importance of glycogenesis

Answer 2

• Occurs when glucose levels are too high
• Used in storage of energy

Question 3

Draw glycogenesis

Answer 3

Question 4

cAMP-dependent protein kinase A (PKA) is activated by…

Answer 4

Glucagon

Question 5

Steps of hormonal regulation

Answer 5

1. Glucagon/adrenalin-binding receptors bind hormones → First messengers
2. Inactive GDP → active with hormone binding
3. GTP bound to α-subunit​
4. Activated α-subunit​ dissociates
5. Adenylate cyclase activated
6. GTP → GDP
7. α-subunit​ inactivated

Question 6

Hormonal regulation of glycogenesis by insulin

Answer 6

1. Insulin receptor → PIP3
2. PIP3 activates PKB
3. Active PKB activates phosphodiesterase
4. This degrades + decreases cAMP
5. Dephosphorylation
6. Activation of glycogen synthase
7. Glycogenesis

Question 7

Insulin:

• Stimulation of glycogen synthesis
• Inhibition of glycogen degradation

Answer 7

1. Insulin bound to the receptor
2. PI3-K activated
3. PIP2 → PIP3 second messenger
4. PKB inactive → PKB active
5. Phosphodiesterase inactive → Active
6. cAMP → AMP
7. PKA active → Inactive
8. Glycogen synthase → Active
9. Glycogen phosphorylase → Inactive

Question 8

Give the steps of parallel regulation of glycogenolysis and glycogenesis in the liver + muscle

Answer 8

1. Glycogen phosphorylase active → Inactive
2. Phosphodiesterase activated by insulin
3. Glycogen synthase active → inactive
4. Adenylate cyclase activated by glucagon + adrenalin
5. Step 1 repeats

Question 9

Draw glycogenolysis

Answer 9

Question 10

Regulation of glycogenolysis

Answer 10