Fermentation
Fermentation is a process in which cells are able to regenerate NAD+ and continue glycolysis when there are a low to none oxygen supply and therefore oxidize NADH to NAD+. This process is therefore able to convert sugars into gases, acids or alcohols. The fermentation of alcohol (Ethanol fermentation) is a form of fermentation that eukaryotes use to obtain they're source of energy. Alcohol fermentation is a process in which sugar (glucose) is decarboxylated creating carbon dioxide and ethanol. This form of fermentation is referred to as an anaerobic process which is another process which is only possible with the absence of oxygen. Alcohol fermentation and yeast is a reaction in which many commercial products begin. With yeast it is able to allow bread dough to rise, and it is involved with the creation of beer and wine. During alcohol fermentation the yeast causes the sugars in the dough to create CO2 and ethanol. CO2 gas in this process causes the breads dough to rise.
Ethanol metabolism
Ethanol is metabolized primarily in the liver when consumed. This process starts by a cytocolic enzyme, dehydrogenase (ADH). The reaction of ADH results in the conversion of NAD+ to NADH. The reaction rate of this process is limited by the activity of the ADH. the toxic affects of alcohol consumption: Acetaldehyde is then converted by aldehyde dehydrogenase (ALDH) causing another conversion of NAD+ to NADH. Aldehyde dehydrogenase works in the mitochondria of a cell to remove hydrogen from the acetaldehyde to produce and acetic acid. Acetate can then either be converted in the liver or muscles and lungs into acetyl COA while consuming energy and converting ATP to AMP. This can either stay in the liver and synthesize fatty acids or be used through engery and enter the TCA cycle. An alternate pathway for ethanol to convert to acetaldehyde is the Microsomal Ethanol Oxidizing System (MEOS) which is a redox reaction caused by a cytochrome P450 enzyme and ending in a conversion of NADPH+ to NADP+.