Enzymes

  • explain that enzymes are globular proteins that catalyse metabolic reactions
  • state that enzymes function inside cells (intracellular enzymes) and outside cells (extracellular enzymes)
  • explain the mode of action of enzymes in terms of an active site, enzyme/substrate complex, lowering of activation energy and enzyme specificity (the lock and key hypothesis and the induced fit hypothesis should be included)
  • explain how the progress of an enzyme-catalysed reaction may be investigated by measuring rates of formation of products (for example, using catalase) or rates of disappearance of substrate (for example, using amylase)
  • explain the effects of the following factors on the rate of enzyme-catalysed reactions and how in each case this may be investigated:
    • temperature
    • pH (using buffer solutions)
    • enzyme concentration
    • substrate concentration
    • inhibitor concentration
  • explain that the maximum rate of reaction (Vmax) is used to derive the Michaelis-Menten constant (Km) which is used to compare the affinity of different enzymes for their substrates
  • explain the effects of reversible inhibitors, both competitive and non-competitive, on the rate of enzyme activity
    investigate and explain the effect of immobilising an enzyme in alginate on its activity as compared with its activity when free in solution