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2015-01-05 10:37:41

Biology A-Level AQA Unit 1
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  1. What do enzymes do?
    They are catalysts which lower the activation energy through formation of enzyme-substrate complexes
  2. Describe the lock and key model
    The active site has a specific rigid shape. Substrates that are that specific shape can only fit in forming the enzyme-substrate complex, nothing else can fit
  3. Describe the induced fit model
    The active site distorts slightly to fit the substrate, forming more enzyme-substrate complexes
  4. Why is the induced fit model better than the lock and key model?
    The induced fit model shows how the activation energy is lowered. As the active site changed shape, pressure is applied on the substrate which weakens bonds so the activation energy is lowered
  5. How does temperature effect enzymes?
    The temperature increases kinetic energy, so more enzymes and substrates colliding and forming enzyme-substrate complexes, increasing the rate of reaction
  6. How does pH effect enzymes?
    • pH effects the amino acids in the active site, if it changes, the shape changes, so no enzyme-substrate complex and rate of reaction slows
    • Can cause bonds in tertiary structure to break, changing shape etc
  7. What is a competitive inhibitor?
    What happens if you increase the concentration?
    • It is similar to the substrate, but it takes its place therefore stopping enzyme-substrate complexes.
    • Increased concentration of the inhibitor means reduced enzyme-substrate complexes
  8. What is a non-competitive inhibitor?
    They attach themselves on the enzyme at a place other than the active site, it alters the shape of the enzyme so the active site changes and substrate can no longer fit