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1.1 identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates

identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates

  • Enzymes are biological catalysts. This means that they lower the energy required to start a chemical reaction within a cell but do not get used up by that reaction. Every reaction and process within a cell (metabolism) is controlled by a specific enzyme.
  • Enzymes are globular proteins whose shapes are specialised so that other chemicals (substrates) can form a temporary bond with them. There are two models used to show how an enzyme work:
  • One model used to illustrate the action of an enzyme is the lock-key model. This is where only one small part of the enzyme molecule can form a complex with the substrate. This part of the molecule is called the active site. Only a specific substrate(s) can bond in that site and this makes the enzyme specific to that substrate.image1
  • The induced fit model, a more recent modification on the lock-key model, proposes that the active site slightly changes its shape to accommodate the substrate perfectly.image2