Digestion

• Enzymes are biological catalysts meaning they speed up chemical reactions in living organisms.
• Enzymes have a space within the protein molecule called the active site.
• Each enzyme catalyses a specific reaction.
• Enzymes work best at a specific temperature and pH called the optimum.
• A model used to explain how enzymes work is the 'lock and key theory'.
• The active site changes shape if there is high temperatures and extremes of pH.
• High temperatures can cause an irreversible and permanent change this is called denaturing.
• If the active site (the lock) has temporarily changed shape or is denatured, the enzyme will not work. The substrate (the key) will no longer fit into the active site (the lock).