At first glance, fermentation of pyruvate to lactate might appear to be an optional add-on reaction to glycolysis. After all, couldn't cells growing in the absence of oxygen simply disregard pyruvate as a waste product? In the absence of fermentation, which products deried 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?