Mutations are changes in the nucleotide sequence of the DNA as compared with a wild type sequence.

Mutations are categorized according to how they change the order of bases:

  • Substitution: one base is replaced by another

  • Deletion: one or more bases are deleted

  • Insertions: one or more bases are inserted

Mutations in coding sequences are categorized according to their effect on the protein:

  • Synonymous or silent mutation: a substitution that does not change the amino acid

  • Non-synonymous or missense mutation: a substitution that changes the amino acid

  • Nonsense mutation: generates a stop codon

  • Frameshift mutation: insertion or deletion not divisible by 3 that alters the reading frame

DNA sequencing DNA test

Theory Overview