Mutations

Cards (11)

  • Gene mutation
    Alteration of a base sequence in DNA
  • Gene mutations are likely to occur when DNA is replicating, which happens in interphase of the cell cycle
  • Mutation impact

    Changes the amino acid sequence (primary structure) in the polypeptide chain, altering the 3D shape and function of the protein
  • Mutagenic agents

    • High energy ionizing radiation (alpha, beta, X-rays, gamma rays)
    Carcinogens (chemicals like tobacco smoke, mustard gas, peroxides)
  • Exposure to mutagenic agents increases the risk of spontaneous mutations, but does not guarantee a mutation will occur
  • Types of gene mutations
    • Addition (frame shift)
    Deletion (frame shift)
    Substitution (sometimes silent)
    Inversion
    Translocation
  • Addition mutation

    One DNA nucleotide is accidentally added, causing a frame shift in the subsequent triplets
  • Deletion mutation

    One DNA nucleotide is deleted, causing a frame shift (to the left) in the subsequent triplets
  • Substitution mutation
    One DNA nucleotide is swapped for another, sometimes resulting in a different amino acid but sometimes a silent mutation
  • Inversion mutation

    A section of DNA detaches and rejoins in the reverse orientation
  • Translocation mutation

    A section of DNA breaks off one chromosome and attaches to a different chromosome