Enzymes

• Enzymes control cell reactions
• Enzymes are specific

  • A substrate is specific to an enzymes active site
  • This is known as the Lock and Key theorem

  
• Enzymes

  • Optimum temperature = 37C
  • Optimum pH = pH7
• Amylase


  • Breaks down starch to maltose
• Catalase

  • Catalyses the breakdown of hydrogen peroxide into water and oxygen

  1. Use a pipette to add a set amount of hydrogen peroxide to a boiling tube
  2. Put the tube in a water bath at 10C
  3. Add a source of catalase to the hydrogen peroxide and quickly attach a bung
  4. Record how much Oxygen is released in the first minute. Repeat 3 times and calculate a mean
  5. Repeat at 20C, 30C... etc.
  6. Control any variable (eg. pH, size of pieces...)
  7. Calculate the mean rate of reaction by dividing the mean volume of oxygen by the time taken

  
• Amylase experiment

  1. Put a drop of iodine into each well
  2. Every 10 seconds, drop a sample of the mixture into a well using a pipette
  3. If the mixture contains starch, the iodine changes from a browny-orange to blue-black