Question

What is fermentation? How does it happen?What is Glycolysis?

Answer 1

Fermentation
Anaerobic organisms lack a respiratory chain. They must reoxidize NADH produced in Glycolysis through some other reaction, because NAD+ is needed for the Glyceraldehyde-3-phosphate Dehydrogenase reaction (see above). Usually NADH is reoxidized as pyruvate is converted to amore reduced compound.
The complete pathway, including Glycolysis and the re-oxidation of NADH, is called fermentation.

Glycolysis is series of reactions that extract energy from glucose by splitting it into two three-carbon molecules called pyruvates, with the production of two molecules of ATP.. In aerobically respiring organisms or cells, glycolysis is the first step of cellular respiration. However, glycolysis doesn’t require oxygen, and many anaerobic organisms (organisms that do not use oxygen) also have this pathway. In aerobic organisms, pyruvate produced in Glycolysis is oxidized to $C{O}_2$ via Krebs Cycle, and the NADH produced in Glycolysis and Krebs Cycle is reoxidized via the respiratory chain, with production of much additional ATP.