Enzymes

• Enzymes


  Chemical reactions are what make you work. And enzymes are what make them work.
• Enzymes


  • They are catalysts produced by living things
  • They reduce the need for high temperatures and only speed up useful chemical reactions in the body
• Catalyst


  A substance which increases the speed of a reaction, without being changed or used up in the reaction
• Enzymes


  • They are large proteins made up of chains of amino acids folded into unique shapes
  • Their unique shape allows them to catalyse specific reactions
• Active site


  The part of an enzyme with a unique shape that fits the substance involved in a reaction (the substrate)
• Lock and key model

  The substrate has to fit into the enzyme's active site for the reaction to be catalysed
• Induced fit model


  The active site changes shape a little as the substrate binds to it to get a tighter fit
• Enzymes


  • They only catalyse one specific reaction
  • They need the right temperature and pH conditions to work properly
• Increasing temperature


  Increases the rate of enzyme-catalysed reactions at first
• Temperature getting too high


  Breaks the bonds holding the enzyme together, changing its shape and denaturing it
• Optimum temperature


  The temperature at which an enzyme works best
• pH being too high or too low


  Interferes with the bonds holding the enzyme together, changing its shape and denaturing it
• Optimum pH


  The pH at which an enzyme works best
• Investigating the effect of pH on enzyme activity

  1. Add amylase and buffer solution to a boiling tube

  2. Add starch solution and start a timer

  3. Take samples every 30 seconds and test for starch with iodine

  4. Repeat with different pH buffers

  5. Calculate the rate of reaction
• Rate of reaction


  A measure of how much something changes over time, calculated as the change in amount divided by the time taken
• Digestive enzymes


  • Carbohydrases (e.g. amylase)
  • Proteases (e.g. pepsin)
  • Lipases
• Carbohydrases


  Enzymes that convert carbohydrates into simple sugars
• Proteases


  Enzymes that convert proteins into amino acids
• Lipases


  Enzymes that convert lipids into glycerol and fatty acids
• Places digestive enzymes are produced

  • Salivary glands
  • Pancreas
  • Small intestine
  • Stomach
• Bile


  • Produced in the liver, stored in the gallbladder, and released into the small intestine
  • Neutralises stomach acid and emulsifies fats
• The whole digestive system has different parts that work together to break down food using enzymes