Mutations

• Mutation


  A change to a base in the DNA sequence
• Mutations happen all the time
• A single base change in the DNA sequence

  Does not change the amino acid sequence of the protein
• A different mutation in the DNA sequence


  Changes the amino acid sequence and alters the shape of the protein
• Mutations that change the shape of a protein


  • Can have a dramatic effect on the function of the protein
  • For example, the active site of an enzyme may change shape so it can no longer bind to the substrate
  • If a mutation changes the shape of a structural protein such as collagen, it may lose its strength
• Non-coding regions of DNA


  Regions that switch genes on and off, telling genes when to produce proteins
• Mutations in non-coding regions


  Can affect how genes are switched on or off, for example, a gene may be turned on when it should be turned off
• Uncontrolled mitosis leading to cancer can be a significant effect of a gene being turned on when it should be turned off