Final answer:
The molecule made during glycolysis that is utilized in fermentation is pyruvate, which can be reduced to lactic acid or ethanol. Through this process, NAD* is regenerated from NADH, allowing glycolysis to proceed even without oxygen.
Step-by-step explanation:
The molecule made during glycolysis and used in the later steps of fermentation is pyruvate. This molecule can be further reduced to lactic acid or ethanol during fermentation. It is important to note that during glycolysis, a net gain of two ATP molecules is produced, and NAD* is regenerated from NADH, enabling glycolysis to continue. Fermentation allows organisms to harvest energy when oxygen is scarce. Therefore, in the absence of oxygen, the pyruvate produced during glycolysis is crucial for sustaining metabolism.