Enzyme Action

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  • Enzyme Action
    • they alter the rate of reaction
    • an initial boost of energy is required to start the reaction
    • globular proteins that act as catalysts
    • they do not make reactions happen they just change the speed at which they do
    • they can be reused and are effective in small amounts
    • the minimum amount of energy needed to activate the reaction is called the activation energy
    • Lock and Key theory
      • one limitation is that the enzyme is a rigid structure
      • enzymes are specific in the reactions that they catalyse
      • the substrate has a complementary shape to the active site
      • each substrate will only fit a specific active site
    • enzymes work by lowering the activation energy
      • enzymes allow the reaction to take place at a lower temperature
    • Enzyme structure
      • the enzyme has a small functional area called the ACTIVE SITE
      • they are globular proteins with a specific 3-D structure
      • the active site forms a small depression in the larger enzyme molecule
      • the molecule on which the enzyme acts is called the SUBSTRATE
      • the substrate fits into the active site forming am enzyme-substrate complex
    • Induced Fit Model
      • the enzyme puts a strain on the substrate, this strain distorts the bond
      • the enzyme is flexible and can mould itself
      • this lowers the activation energy needed to break the bond
      • rather than being rigid, the enzyme changes shape to fit the substrate
      • changes in the enzymes environment is likely to change its shape


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