B3 - Effect of temp on action of enzyme

• Enzymes 


  Proteins that act as biological catalysts, speeding up the rates of reaction in the body. The enzymes themselves are not used up in the reaction. Enzymes can both build up and break down molecules
• How enzymes work 


  In enzyme action, the substrate fits snugly into the active site of the enzyme. This tight fit enables the enzyme to catalyse the reaction and split the substrate into its products.

  The action is referred to as lock and key model due to the importance of the tight fit between the enzymes active site and the substrate. This tight fit explains the process of enzyme specificity - each enzyme is specific in that it will only work on one substrate
• Factors affecting enzyme action

  Temperature, pH and enzyme concentration all affect enzyme action. The maximum rate of enzyme activity is described as the optimum
• Lock and key 


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• Temperature

  • At lower temperatures the enzymes and substrates move very slowly (low kinetic energy) so there are fewer collisions and therefore enzyme activity is low
  • Maximum enzyme activity occurs at the optimum temperature of 35-40 degrees Celsius
  • At higher temperatures, above the optimum, the enzymes are progressively denatured. The increased temperature changes the shape of the active site and it no longer fits the substrate. Rate of reaction is slower
• Temperature graph 


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• Inhibitors


  Some molecules can fit loosely into an enzymes active site - they may not be an exact fit, but they can fit well enough to stop the normal substrate from fitting. These are referred to as inhibitors. They are not broken down by the enzyme