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  • Created by: zoolouise
  • Created on: 26-05-16 08:56


The term 'metabolism' refers to all of the reactions of the body. Reactions occur in sequences called metabolic pathways. These includes:

  • Anabolic reactions - building up of molecules e.g. protein synthesis
  • Catabolic reactions - breaking down of molecules e.g. digestion

In cells thousands of reactions are occuring simulataneously and they need to work effeciently, meaning at a rate which can sustain life. Metabolic reactions are controlled by enzymes.

What are enzymes

  • Globular proteins - they have a spherical tertiary structure held in place by hydrogen/ionic/disulphide bridges and hydrophobic bonds
  • A specific 3D shape giving the enzyme many of its properties
  • Biological catalysts made by living things, they speed up reactions
  • They aren't used up in reactions
  • They aren't changed in reactions
  • They have a high turn-over, they catalyse many reactions per second
  • They're soluble due to their hydrophillic R group

Why are enzymes important

  • Enzymes catalyse reactions that are energetically favourable and would happen anyway
  • They make these reactions happen at a rate which can support life

How do enzymes work

  • Enzmes react with another molecule called a substrate
  • Each enzyme has its own special shape, with a specific region called the active site


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