Question

A cell shifts to fermentation when there is insufficient oxygen sufficient oxygen

Answer 1

The answer is Insufficient oxygen.

Whenever there is less oxygen present , a cell fully depends on glycolysis to produce ATP. During glycolysis glucose and NAD+ is used to produce pyruvate , NADH and ATP. As less oxygen is present this NADH can't go through electron transport chain to produce ATP and synthesis of NAD+. So as the glycolysis process continues, due to continues formation of NADH there is a lack of NAD+ molecules. During fermentation process this NAD+ molecules are regenerated so that the Glycolysis process can go on. So that the production of ATP doesn't stop.

Glycolysis can be summarized by Glucose + NAD++ 2ADP +P: Pyrouvate +2ATP + NADH +H) Now fermentation is of two types 1. Ethanol fermentation: NADH+H+ NAD y Ethanol Pyruvate Acetaldehyde COR 2. Lactic acid fermentation NADH NADH+H+ Lactate. Pypurate Lactate Dehydrogenase So, there is regenereation of NADt molecules. So, thood the glycolysis process can go on fluently,