2.3.1 - Action of enzymes

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Enzymes introduction:

  • Enzymes are biological catalysts. They catalyse reactions in your body, e.g. digestion and respiration 
  • Enzyme action can be intracellular - within cells or extracellular - outside cells. 
  • They are globular proteins, and have an active site, which has a specific shape. The active site is the part of the enzyme where the substrate molecules binds to. The specific shape of the active site is determined by the enzyme's tertiary structure
  • For the enzyme to work, the substrate has to fit into the active site (its shape has to be complimentary). If the substrate shape doesn't match the active site, the reaction won't be catalysed. This means that enzymes work with very few substrates 

Enzymes and activation energy:

  • The activation energy is the amount of energy required to supply the chemicals before a reaction will start. Its often provided as heat 
  • Enzymes reduce the amount of activation


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