Question

At first glance, fermentation of pyruvate to lactate appears to be an optional add-on reaction to glycolysis. After all, could cells growing in the absence of oxygen not simply discard pyruvate as a waste product? In the absence of fermentation, which products derived from glycolysis would accumulate in cells under anaerobic conditions? Could the metabolism of glucose via the glycolytic pathway continue in the absence of oxygen in cells that cannot carry out fermentation? Why or why not?

Answer 1

Answer:

No, glycolysis can not be continued without fermentation in the absence of oxygen.

Explanation:

In the absence of oxygen, cells perform fermentation to oxidize NADH into NAD+. NAD+ is required during the conversion of glyceraldehyde 3 phosphate into 1,3 bisphosphoglycerate. Fermentation reduces pyruvate and oxidizes NADH so that the NAD+ supply is continued to ensure continuity of glycolysis.

If fermentation does not occur under anaerobic conditions, cells will accumulate pyruvate and NADH. Glycolysis could not be continued in the absence of NAD+.