Mutations

Cards (6)

  • Mutations are changes in the DNA that can result in no protein or an altered protein being synthesized
  • Single gene mutations:
    • Substitution: the replacement of one base, involving the alteration of a DNA nucleotide
    • Insertion: the addition of one base sequence as a result of substitution
    • Deletion: the removal of one base
  • Substitution mutations, Insertion, and Deletion Mutations
  • Effects of mutations on DNA sequence:
    • CGAcc6AcT -> CGAccGAC: one base added, one base change
    • L -> LL: one base change
    • CGAccGAA -> TCGACCC: three effects:
    • Missense: one amino acid is changed for another
    • Nonsense: premature stop codon, resulting in frame-shift mutations
    • Splice-site: introns may be retained or exons removed, causing a major effect on protein structure
  • Chromosome Structure Mutations:
    • Translocation: non-homologous chromosomes alter the number or structure of chromosomes
    • Inversion: homologous chromosomes reverse their structure
    • Duplication: homologous chromosomes have a section added
    • Deletion: homologous chromosomes have a section removed
  • Substantial changes in chromosome structure are often lethal
    • Deletion: a section of a chromosome is removed
    • Duplication: a section of a chromosome is added
    • Inversion: a section of a chromosome is reversed
    • Translocation: a section of a chromosome is added to a non-homologous chromosome, affecting genes like clotting factors and causing disorders like Haemophilia A or Cri-du-chat syndrome