Question

1. When the blood glucose concentration is low, the pancreas secretes glucagon to signal the liver to produce glucose and glucose-1-phosphate. Which metabolic steps are involved in this biosignaling pathway?

1. Inactivation of glycogen synthase via phosphorylation by protein kinase A
2. Activation of glycogen synthase via phosphorylation by protein kinase A
3. Activation of phosphofructokinase-2 via phosphorylation by protein kinase A
4. Activation of fructose-2,6-bisphosphatase via phosphorylation by protein kinase A
5. Activation of phosphofructokinase-1 by fructose-2,6-bisphosphate
6. Inhibition of fructose-1,6-bisphosphatase by fructose-2,6-bisphosphate
7. Inactivation of pyruvate kinase via phosphorylation by protein kinase A

1. II
2. I and IV
3. I, III, V, VI, and VII
4. I, IV, and VII

2. Which biochemical steps are involved in the glucagon-triggered activation of gluconeogenesis?

1. Activation of fructose-2,6-bisphosphatase via phosphorylation by protein kinase A
2. Inactivation of fructose-2,6-bisphosphatase via phosphorylation by protein kinase A
3. Activation of phospholipase C
4. Inactivation of phospholipase C
5. Release of calcium
6. Sequestration of calcium
7. Phosphorylation of FoxO1
8. Dephosphorylation of FoxO1
9. Increased expression of PEP carboxykinase
10. Phosphorylation of PEP carboxykinase
11. Formation of additional PEP, which is a glycolytic intermediate
12. Degradation of PEP, which is a glycolytic intermediate

1. I, III, V, VII, IX, and XI
2. II, III, V, VII, IX, and XI
3. I, III, VI, VII, IX, and XII
4. I, III, V, VII, X, and XI

Answer 1

1) Correct Answer: (b) I and IV

Glycogenolysis: It is the process by which glycogen stored in liver and muscle cells, breaks down to form glucose.

Inactivation of glycogen synthase via phosphorylation by protein kinase A and activation of fructose 2,6 bisphosphate via phosphorylation of protein kinase A.

Glycogen synthase helps in the formation of glycogen from glucose. The inhibition of Glycogen synthase is essential to produce glucose.

2) Correct Answer: (a) I, III, V, VII, IX and XI

Gluconeogenesis: It is the process through which glucose is generated from a non-carbohydrate carbon substrate. The process involves a cascade of mechanisms producing glucose.