Mutations

• What are the types of mutation?

  • Substitution
  • Deletion
  • Inversion
  • Addition
  • Duplication
  • Translocation
• What is base substitution?


  One DNA nucleotide is replaced by another. Has one of three effects:

  • Forms a stop codon
  • Changes the codon, so codes for a different amino acid
  • Forms a different codon but produces the same amino acid
• What is it called when a different codon is formed but produces the same amino acid?

  Silent mutation
• What is base deletion?


  Loss of a nucleotide base from DNA, causing a frame shift to the left
• What is an inversion?


  Group of bases are separated from the DNA sequence and rejoin at the same position but flipped around
• What is base duplication?


  Bases are repeated, producing a frame shift to the right
• What is translocation of bases?

  A group of bases are separated from the sequence on one chromosome and are inserted onto a different chromosome
• What are the causes of mutations?

  Natural mutations

  Mutations by mutagenic agents
• What are some mutagenic agents?

  Ionising radiation

  Chemicals