mutations 6

• Mutations


  Changes in DNA that can result in no protein or altered protein being synthesised
• Types of single gene mutations

  • Substitution of nucleotides
  • Insertion of nucleotides
  • Deletion of nucleotides
• Types of mutations caused by substitutions

  • Missense mutations - result in one amino acid being changed for another
  • Nonsense mutations - result in premature stop codon being produced which results in a shorter protein
  • Splice site mutations - result in some introns being retained and/or some exons not being included in the mature transcript
• Frameshift mutations


  Cause all of the codons and all of the amino acids after the mutation to be changed, having a major effect on the structure of the protein produced
• Types of chromosome mutation

  • Duplication - A section of a chromosome is added from its homologous partner
  • Deletion - A section of the chromosome is removed
  • Inversion - A section chromosome is reversed
  • Translocation - A section of a chromosome is added to a chromosome, not its homologous partner
• Duplication allows potential beneficial mutations to occur in duplicated gene whilst the original gene can still be expressed to produce its protein