21.2 Biotechnology

Yeast (Saccharomyces cerevisiae) anaerobic respiration produces ETHANOL + CO₂ from glucose — used in biofuel production (ethanol distilled from sealed fermenters → renewable fuel) and bread-making (CO₂ trapped by gluten makes dough rise; ethanol evaporates during baking). Industrial enzymes: pectinase digests pectin in fruit cell walls to release more juice and clarify it; biological washing powders contain a cocktail of enzymes — protease (protein stains: blood, sweat, egg), lipase (fat stains: butter, oil), amylase (starch stains: pasta sauce, gravy) — that work at cool temperatures (30–40 °C) to save energy. HL extensions: lactase (immobilised on alginate beads → lactose-free milk), industrial fermenters producing insulin (genetically modified E. coli), penicillin (Penicillium fungus) and mycoprotein (Fusarium fungus → Quorn), and the 5 controlled fermenter conditions (temperature, pH, oxygen, nutrient supply, waste products).