Question

What enzyme is found in the liver but missing from muscle and what is the significance of this?

a) Creatine kinase is found in the liver but not in muscle
b) Hexokinase is found in muscle but not in the liver
c) Glycogen synthase is found in the liver but not in muscle
d) Phosphoenolpyruvate carboxykinase (PEPCK) is found in the liver but not in muscle

Answer 1

d) Phosphoenolpyruvate carboxykinase (PEPCK) is an enzyme found in the liver but missing from muscle. It plays a crucial role in gluconeogenesis, helping to maintain blood glucose levels by converting non-carbohydrate sources into glucose.

Step-by-step explanation:

d) Phosphoenolpyruvate carboxykinase (PEPCK) is found in the liver but not in muscle. This enzyme plays a crucial role in the process of gluconeogenesis, which is the production of glucose from non-carbohydrate sources. In the liver, PEPCK helps maintain blood glucose levels by converting lactate, amino acids, and glycerol into glucose.

Since muscle tissue does not participate in gluconeogenesis, it does not require the presence of PEPCK. Instead, muscle tissue relies on glycolysis, a process that breaks down glucose into energy.

The absence of PEPCK in muscle is significant because it ensures a concentration of this enzyme in liver tissue, where it is critically involved in regulating blood glucose levels.