Question

In anoxic conditions, pyruvate gets converted to lactate. One important reason for the conversion is that...

a. it generates an ATP molecule
b. it stimulates the citric acid cycle by converting FAD+ to FADH2
c. it converts NADH to NAD+ which prevents delivery of high energy electrons to the electron transport chain
d. it generates free protons for use in the electron transport chain
e. lactate is used for protein synthesis

Answer 1

The important reason for the conversion of pyruvate to lactate in anoxic conditions is to recycle NAD+ from NADH. This process allows glycolysis to continue, which is critical for ATP production when oxygen is scarce.

Step-by-step explanation:

In anoxic conditions, the conversion of pyruvate to lactate is essential because it permits the continuation of glycolysis. This conversion is critical as it facilitates the recycling of NAD+ from NADH, which is a crucial step in the glycolytic pathway. The correct answer to why pyruvate is converted to lactate in anoxic conditions is that it converts NADH to NAD+, allowing the glycolytic pathway to continue.

It is not because it generates an ATP molecule; rather, the conversion keeps the pyruvate levels low to maintain glycolysis and recycles NAD+ which is necessary for the glycolytic pathway. The lactic acid produced can diffuse into the plasma and ultimately be transported to the liver to re-enter metabolic cycles, a process known as the Cori cycle. Lactate itself is not used for protein synthesis, nor does it stimulate the citric acid cycle under these conditions.