Question

12). Insulin will cause a decrease in activity of which of following enzymes?

A. Glucokinase

B. Glycogen phosphorylase

C. Glucose transporter

D. Phosphofructokinase-1

Answer 1

Insulin will cause a decrease in activity of (B) glycogen phosphorylation

EXPLAINATION  FOR THE ANSWER

Insulin is secreted by beta cells of pancreatic islets. It is a peptide hormone. It promotes absorption of carbohydrates, mainly glucose by liver and skeletal muscles and thus regulates metabolism of carbohydrates, proteins and fat.

When the glucose level increases in body insulin is released by pancreas which results in its uptake up the body cells. When the glucose levels ate low in body insulin secretion is inhibited.

When glucose levels increases in body, insulin promotes glycogen synthesis by activity of the hexokinase enzyme — glucokinase. It causes phosphorylation of glucose to glucose 6 phosphate.

Insulin also activates phosphofructokinase which results in glycogen synthesis.  

Insulin also stimulates GLUT 4 transporter into the muscles and fat tissue which results in glucose entey into the cell.

Glycogen phosphorylase breaks down to glycogen into glucose. When the glucose level is high in blood, insulin secretion is stimulated. Insulin controls the glycogen phosphorylase by exerting an inhibiting effect and thus inhibiting glycogenolysis.