mutations

• mutation

  change in the base sequence of DNA
• what increases the risk of mutations occurring

  1. carcinogens - chemicals that can cause cancer
  2. certain types of radiation (X-rays and gamma rays)
• what is meant if a gene is expressed

  it is switched on

  means the cell is actively producing the proteins that the gene codes for
• non-coding DNA

  DNA that does not code for a protein

  often has a role in switching genes on and off so mutations in these areas of DNA may affect how genes are expressed
• if a gene has a mutation what could happen to the protein it codes for

  the change in the base sequence could cause a different sequence of amino acids to be coded for

  This could cause the protein to fold into a different shape, which could mean that it no longer carries out its function
• insertion mutation

  an extra base is added into the sequence

  this can cause a frame shift where every subsequent triplet is different
• deletion mutation

  base is removed from the sequence

  can cause a frame shift where every subsequent triplet is different