The chemical equation for the breakdown of lactose by lactase is: C12H22O11 (lactose) + H2O → C6H12O6 (glucose) + C6H12O6 (galactose).
Lactase is the enzyme that catalyzes this reaction, breaking down lactose into its constituent monosaccharides, glucose, and galactose. This process is essential for the digestion of lactose in individuals who are lactose intolerant.