What is the importance of the purine nucleoside cycle?
A) It participates in the conversion of purines into pyrimidines.
B) It generates fumarate, which inhibits the formation of AMP from IMP.
C) It provides fumarate as an anaplerotic enhancement of the citric acid cycle.
D) It inhibits the citric acid cycle in skeletal muscles.
E) It is used in energy metabolism in the liver.

Question

What is the importance of the purine nucleoside cycle?
A) It participates in the conversion of purines into pyrimidines.
B) It generates fumarate, which inhibits the formation of AMP from IMP.
C) It provides fumarate as an anaplerotic enhancement of the citric acid cycle.
D) It inhibits the citric acid cycle in skeletal muscles.
E) It is used in energy metabolism in the liver.

Quizplus · Accepted Answer

The purine nucleoside cycle provides fumarate as an anaplerotic enhancement of the citric acid cycle. Anaplerosis refers to replenishing the intermediates of a metabolic pathway. Fumarate is a key intermediate in the citric acid cycle and its availability through the purine nucleoside cycle can enhance the cycle's activity.

Answer: E
 The purine nucleoside cycle is used in energy metabolism in the liver. It allows the liver to generate ATP by breaking down purines in the absence of oxygen. This is important for liver function, as the liver is one of the major organs involved in energy metabolism and is often exposed to low oxygen conditions. The purine nucleoside cycle provides an alternate pathway for ATP production in these conditions.

What Is the Importance of the Purine Nucleoside Cycle