Question

please answer 1-6 :)

1. Glycogen metabolism is regulated, up to a point, by a cyclic AMP cascade. At what point do glycogen synthesis pathways diverge from glycogen degradation pathways?

a. Protein kinase A leads to the activation of glycogen degradation, and also to the inhibition of glycogen synthase by conversion from b to a.

b. Phosphorylase kinase converts phosphorylase b to phosphorylase a and glycogen synthase a to glycogen synthase b.

c. Protein kinase A leads to the activation of glycogen degradation, and also to the inhibition of glycogen synthase by conversion from a to b.

d. Phosphorylase kinase converts phosphorylase a to phosphorylase b and glycogen synthase a to glycogen synthase b.

e. Cyclic AMP converts inactive PKA to active PKA, causing the inactivation of phosphorylase kinase.

2. The activated glucose donor of glycogen synthesis is:

a. glucose 1,6-bisphosphate.

b. uridine diphosphate glucose.

c. glucose 1-phosphate.

d. uridine triphosphate glucose.

e. glucose 6-phosphate.

3. A complete oxidation of a glucose residue derived from glycogen yields _____ ATP.

a. 4

b. 7

c. 31

d. 2

e. 11

4. How many molecules of ATP are hydrolyzed to incorporate one dietary glucose molecule into glycogen?

a. 2

b. 6

c. 8

d. 4

e. 1

5. What enzymes regulating liver-glycogen metabolism predominate in the fasting state? Select all that apply.

a. glycogen phosphorylase a

b. glycogen phosphorylase b

c. glycogen synthase b

d. protein phosphatase 1

e. glycogen synthase a

6. What protein is activated in the cytoplasm due to activation of the insulin receptor?

a. protein kinase A

b. protein phosphatase 1

c. glycogen phosphorylase

d. glycogen synthase kinase

e. insulin-receptor substrate

Answer 1

1. C is the right answer. Glycogen synthesis pathways diverge from glycogen degradation pathways when protein kinase A leads to activation of glycogen degradation and also inhibition of glycogen synthase by conversion from a to b.

2. B is the right answer. The activated glucose donor in the glycogen synthesis is uridine diphosphate glucose. It is the activated form of glucose and glycogen synthase helps in transferring the glucose to growing glycogen chain.