Of what importance are lactic acid feremtation and alcoholic fermentation to the cells that use these pathways

Answer 1

glycolysis takes place anerobically normally to give pyruvate. in this process it gives out 4 ATPs consuming 2ATPs hence making the net gain to 2 ATPs.

this pyruvate in the presence of oxygen (aerobic respiration) is converted to acetyl co A which then enters the krebs cycle to give more ATPs.

in the absense of oxygen (anerobic repiration or fermentation) the pyruvate is converted to lactic acid which is an end product and accumulates without any further use to the cell.

since excess pyruvate in the cell acts like a feedback mechanism to the cell to prevent further breakdown of glucose to pyruvate, this pyruvate must be removed or converted to another form so that glycolysis takes place and more ATP is produced. now although krebs cycle would produce more ATP then glycolysis, but in the absence of oxygen, the cells still require energy and hence they convert the excess pyruvate to lactic acid inorder for those couple of ATPs that can be produced. thus fermentation helps the cells to sustain life by producing energy even in the absence of oxygen.

Answer 2

Fermentation takes away the end products of glycolysis so that glycolysis can continue. Specifically, fermentation returns the NAD to glycolysis. It's important for glycolysis to continue because glycolysis yields a net gain of 2 ATP from each glucose molecule. Without fermentation, even that would come to a halt, and no glucose would be broken to yield any glucose at all.

So, even though fermentation and glycolysis only give a little ATP compared with the much larger gain of aerobic respiration, it's still better than nothing.

Answer 3

Both are anaerobic processes that allow ATP production to continue in the absence of oxygen.