3.4

• Catalyst


  A substance that increases the rate of a chemical reaction without being consumed or altered itself
• Enzyme


  A biological catalyst that speeds up chemical reactions in living organisms
• Active site of an enzyme

  The specific region on an enzyme molecule where the substrate binds and the reaction occurs
• Enzymes


  • They are made up of chains of amino acids folded together to make large complex molecules
  • The shape of the active site is vital for the enzyme to function and bind to a specific substrate
• How enzymes work


  1. Substrate fits into the active site

  2. Substrate splits into products which leave the active site

  3. Enzyme ready to use again
• Enzymes


  They do not change the reaction, they just make it happen faster
• Types of metabolic reactions catalysed by enzymes

  • Building large molecules from smaller ones
  • Changing one molecule into another
  • Breaking down large molecules into smaller ones
• Each cell can have hundreds of chemical reactions going on at once, each controlled by a different specific enzyme</b>
• Inorganic catalyst


  • Manganese(IV) oxide
• Enzyme catalyst


  • Catalase from raw liver or potato
• Adding a catalyst (inorganic or enzyme)


  Increases the rate of decomposition of hydrogen peroxide
• Hydrogen peroxide is a poisonous compound that needs to be broken down quickly into harmless oxygen and water