How does yeast turn sugar into alcohol?

The answer

Fermentation is an anaerobic metabolic process where yeast (Saccharomyces cerevisiae) breaks down glucose to produce ethanol and carbon dioxide as byproducts. When oxygen is scarce, yeast converts one molecule of glucose into two molecules of ethanol and two molecules of CO₂, harvesting a small amount of energy in the process. Humans have exploited this biochemistry for at least 9,000 years to produce beer, wine, and bread. The CO₂ makes bread rise, while the ethanol makes beverages alcoholic.