Enzymes can work in mild conditions they work fast and remain unchanged in the reaction. Oxidoreductases: catalyze oxidations or reductions (we want to avoid oxidation in food science) Hydrolases: catalyze the hydrolytic splitting of substrates. Enzymes are expressed only under specific conditions (ph, substrate, temp, etc) Units mol of substrate produced per unit time. Forms of an enzyme that catalyze the same reaction but have different physiochemical characteristics (ph optima, temperature optima, response to inhibitors, etc. ) Induced fit conformation of enzyme is changed by binding to substrate conformation is flexible and holds substrate correctly to accomplish its goal. Zero order adding more substrate won"t do anything velocity is independent of substrate concentration. First order rate is proportional to the first power of substrate concentration (rate = k[s]) V0 initial velocity at substrate concentration [s] Km [s] at half of vmax it also tells us the stability of the enzyme-substrate complex and a higher value means it is less stable.