Alcoholic fermentation

Alcoholic fermentation is the microbial conversion of sugars into ethanol and carbon dioxide. Yeasts use it to regenerate NAD⁺ and obtain energy when oxygen is absent or limited.

Glycolysis: A metabolic pathway that breaks glucose into pyruvate, producing ATP and NADH. It supplies pyruvate and the energy that fermentation helps cells obtain without oxygen.
Wine: An alcoholic beverage produced by fermenting grape juice. Yeasts convert grape sugars into ethanol and carbon dioxide during its production.
Pyruvate: A three-carbon molecule produced by glycolysis and used in several metabolic pathways. It is the direct substrate from which fermentation generates acetaldehyde.
Carbon dioxide: A colorless gas composed of one carbon atom and two oxygen atoms. Its release can raise bread dough and carbonate some fermented drinks.
Pyruvate decarboxylase: An enzyme that converts pyruvate into acetaldehyde and carbon dioxide. It releases the carbon dioxide characteristic of alcoholic fermentation.
Beer: An alcoholic beverage made by fermenting sugars from malted grains, often with hops. Brewing yeast performs alcoholic fermentation in the wort.
NADH: The reduced form of the electron-carrying coenzyme NAD⁺. Fermentation oxidizes NADH so cells can sustain glycolysis.
Ethanol: A two-carbon alcohol produced by fermentation and used in beverages, solvents, and fuels. It is the pathway’s main reduced product and accumulates in alcoholic drinks.
Acetaldehyde: A reactive organic compound formed during ethanol production and other metabolic processes. It is the intermediate that accepts electrons before becoming ethanol.
Bread: A baked food made from dough, commonly raised by yeast or chemical leavening. Carbon dioxide from yeast fermentation expands dough before baking.

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