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• Enzymes

  Catalysts made by living organisms
• Enzymes

  • They are large proteins made up of long chains of amino acids
  • They can fold into different shapes, each shape being a unique enzyme that catalyzes a particular chemical reaction
• How enzymes work

  1. Enzyme has an active site with a unique shape complementary to the substrate

  2. Substrate binds to active site

  3. Enzyme catalyzes the reaction

  4. Products are released
• Substrate

  Reactant in a biological chemical reaction
• Products

  Smaller pieces that a substrate is broken into during a reaction
• Enzymes

  • They speed up chemical reactions without being consumed or permanently altered
  • They are specific, only catalyzing reactions where the substrate fits the active site
• Lock and key model


  Original model where substrate had to fit perfectly into active site, like a key in a lock
• Most chemical reactions in living cells are naturally quite slow
• Increasing temperature to speed up reactions is not feasible as it requires a lot of energy, can damage cells, and speeds up unwanted reactions
• Catalyst

  A substance that increases the speed of a chemical reaction without being changed or used up in the process