• Created by: tia5sos
  • Created on: 01-12-20 09:59
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  • enzymes
    • enzymes control cell reactions
      • 1. cells have thousands of different chemical reactions going on inside them all the time - like respiration, photosynthesis and protein synthesis. Together this makes up the cell's metabolism.
      • 2. these reactions need to be carefully controlled to get the right amount of substances and keep the organism working properly
      • 3.you can usually make a reaction happen more quickly by rising the temperature. This would speed up the useful reactions but also the unwanted ones too. There's also a limit to how far you can raise the temperature inside a living creature before its cells start getting damaged.
      • 4. so living things produce enzymes, which act as biological catalysts.
        • a catalyst is a substance that speeds up a reaction, without being changed or used up in the reaction itself
      • 5. enzymes reduce the need for high temperatures and we only have enzymes to speed up the useful chemical reactions in the body.
      • 6. every different biological reaction has its own enzyme especially for it
      • 7. each enzyme is a protein coded for by a different gene, and has a unique shape which it needs to do its job
    • enzymes are very specific
      • 1. chemical reactions usually involve things either getting split apart or joined together
      • 2. the substrate is the molecule changed in the reaction
      • 3. every enzyme has an active site - the part where it joins on to its substrate to catalyse the reaction.
      • 4. enzymes only work with one substrate usually. The scientific way of saying this is that enzymes have a high specificity for their substrate
      • 5. this is because, for the enzyme to work, the substrate has to fit into the active site. If the substrate's shape doesn't match the active sites shape, then the reaction won't be catalysed (sped up).
        • this is called the lock and key hypothesis, because the substrate fits into the enzyme just like a key fits into a lock.


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