Question

In microbiology, what are 5 facts highlighting the processes of fermentation and cellular respiration?

Answer 1

Fermentation is an anaerobic (in the absence of oxygen) process of breakdown of glucose to release energy. Some living systems instead use an inorganic other than O₂ such as sulfate, as a final electron acceptor for an electron transport chain. This process, called anaerobic cellular respiration, is performed by some bacteria and archaea.

Fermentation and cellular respiration begin the same way, with glycolysis. In fermentation, however, the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle, and the electron transport chain does not run. Because the electron transport chain isn't functional, the NADH made in glycolysis cannot drop its electrons off there to turn back into NAD​+.

The purpose of the extra reactions in fermentation, then, is to regenerate the electron carrier NAD​+​​ from the NADH produced in glycolysis. The extra reactions accomplish this by NADH drop its electrons off with an organic molecule (such as pyruvate, the end product of glycolysis). This drop-off allows glycolysis to keep running by ensuring a steady supply of NAD​+​​.

Anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain, driving ATP synthesis. Some organisms use sulfate SO_4^- as the final electron acceptor at the end ot the transport chain, while others use nitrate (NO​3​−​​),sulfur, or one of a variety of molecules.