Biology P1 - Enzymes

• Enzymes are globular proteins and biological catalysts that lower the activation energy.
• By lowering the activation energy through enzyme-substrate complex the rate of reaction is increased
• Lowering the activation energy is an exothermic reaction
• Tertiary structure of an enzyme is held together by hydrogen and ionic bonds and sometimes disulfide bridges which determine the shape of the active site
• Only substrates which are complimentary in shape to the active will bind to form and enzyme substrate complex
• The enzyme will remain unchanged in the Lock and Key
• The Induced fit model lowers the activation energy by putting a strain on the bond making it easy to break the as it requires less energy
• The Induced fit model suggests that the enzyme can change its shape slightly so it becomes flexible in shape
• In the induced fit model the enzyme is flexible and moulds itself around the substrate
• The effect of substrate concentration


  The RoR increase as collisions between substrate and enzyme molecules are more likely. This will level out as the active site of all enzyme molecules are taken up by substrate molecules. Time is limited for ESC to form the product to release from the active sit. The active sites are either occupied or saturate. To again increase RoR is by adding more enzymes to concentration
• Acids release/form H+ molecules while Alkalis form OH- molecules
• Non-competitive inhibitors are dissimilar in shape and are not complimentary in shape to the substrate which mean ESC can no longer form reducing the rate of reaction.
• A competitive inhibitor is similar in shape and therefore complimentary in shape so it competes to bind with the active site. The RoR is reduced so fewer ESC can form.
• How can enzymes remove stains?

  Enzymes hydrolyse insoluble molecules so they become small and soluble and then water can wash and dissolve the stain
• Effect on Temperature

  RoR increase as an increase in kinetic energy leads to an increase of collisions between atoms. Cycle continues till optimum temperature when it decreases and tertiary structure of enzyme starts to denature because hydrogen and ionic bonds are broken. RoR decrease as substrate is no longer complimentary in shape to active site so there is no way for ESC to form
• Effect on pH


  Can cause denaturation. Hydrogen and ionic bonds are broken, altering the tertiary structure of enzyme and active site. ESC cannot form
• Why would there be no effect on RoR without inhibitor?


  It’s reached the maximum rate at which enzyme can combine with substrate to form ESC so the enzyme is the limiting factor
• A high temperature means when the enzyme works the fastest
• Two variable to control for investigation is the concentration of amylase and volume of substrate conc (also keep the same pH
• Repeating results provides a more reliable mean and anamolous results can be spotted easily