Energy Storage

Question 1

How is glucose stored?

Answer 1

Glycogen

Question 2

Which tissues only use glucose?

Answer 2

RBCs
Neutrophils
Inner cells of kidney medulla
Lens

Question 3

How is glycogen stored?

Answer 3

As granules

Question 4

What is the structure of glycogen?

Answer 4

Polymer of glucose with 1-4 and 1-6 bonds

Branches around protein - glycogenin

Question 5

What is glycogenesis?

Answer 5

Glycogen synthesis

Question 6

What is the process of glycogenesis?

Answer 6

Glucose + ATP -(glucokinase)-> G-6-P + ADP

G-6-P G-1-P

G-1-P + UTP + H2O -(G1P uridylyltransferase)-> UDP-glucose + PPi

Glycogen(n) + UDP-glucose -> glycogen(n+1) + UDP

• glycogen synthase (1-4 bonds)
• branching enzyme (1-6 bonds)

Question 7

What is glycogenolysis?

Answer 7

Glycogen degradation

Question 8

What is the process of glycogenolysis?

Answer 8

Glycogen(n) + Pi -> G-1-P + glycogen(n-1)

• glycogen phosphorylase (1-4)
• debranching enzyme (1-6)

G-1-P G-6-P

Question 9

What is the rate limiting enzyme of glycogen synthesis?

Answer 9

Glycogen synthase

Question 10

What is the rate limiting enzyme of glycogen degradation?

Answer 10

Glycogen phosphorylase

Question 11

What is the effect of glucagon on glycogen metabolism?

Answer 11

Increases glycogen phosphorylase activity

Decreases glycogen synthase activity

Question 12

What is the effect of adrenaline on glycogen metabolism?

Answer 12

Increases glycogen phosphorylase activity

Decreases glycogen synthase activity

Question 13

What is the effect of insulin on glycogen metabolism?

Answer 13

Increases glycogen synthase activity

Decreases glycogen phosphorylase activity

Question 14

What is gluconeogenesis?

Answer 14

Production of new glucose

Question 15

What are the major precursors of gluconeogenesis?

Answer 15

Lactate
Glycerol
Amino acids

Question 16

What are key enzymes of gluconeogenesis?

Answer 16

Phosphoenolpyruvate carboxykinase (PEPCK)
Fructose 1,6-bisphosphatase
Glucose-6-phosphatase

Question 17

What is the effect of glucagon on gluconeogenesis?

Answer 17

Increases

Question 18

What is the effect of insulin on gluconeogenesis?

Answer 18

Decreases

Question 19

What is lipogenesis?

Answer 19

Fatty acid synthesis

Question 20

Where does lipogenesis occur?

Answer 20

Liver

Question 21

How does lipogenesis occur?

Answer 21

Glucose -> pyruvate

Pyruvate enters mitochondria and forms acetyl-CoA + OAA

Condense to form citrate -> cytoplasm

Back to acetyl-CoA + OAA

Acetyl-CoA carboxylase produces malonyl-CoA

Fatty acid synthase complex builds fatty acids from carbon from malonyl-CoA

Question 22

What is lipolysis?

Answer 22

Fat mobilisation

Question 23

How does lipolysis occurs?

Answer 23

Triglycerides broken down by hormone sensitive lipase

Question 24

What activates hormone sensitive lipase?

Answer 24

Glucagon

Adrenaline

Question 25

What inhibits hormone sensitive lipase?

Answer 25

Insulin