Gene mutations

• What is a mutation?

  A mutation is a change in the DNA sequence of a gene, which can result in a change in the protein produced by that gene
• Substitution of bases:

  • a nucleotide in a DNA molecule is replaced by another base
  • can be a silent mutation - the base that is substituted codes for the same amino acid so the gene is not affected
• Deletion of bases:

  • a nucleotide is lost from the DNA sequence
  • causes a frame shift to the left
• Polypolidy:

  • organisms have 3 or more sets of chromosomes instead of 2
• Changes to the the number of individual chromosomes occur when homologous pairs of chromosomes fail to separate during meiosis.

  This is called non-disjunction