noun, plural: silent mutations
Mutation is a change in the nucleotide sequence of a gene or a chromosome. When there is only one nucleotide involved, it is particularly referred to as a point mutation. Point mutation occurring in noncoding sequences often does not result in an altered amino acid sequence during translation. However, if a mutation in the promoter sequence of a gene occurs, the effect may be apparent since the expression of the gene may cause changes in the amino acid sequence, as well as the structure and function of the protein product. Point mutations may be classified based on functionality: (1) nonsense mutation, (2) missense mutation, and (3) silent mutation.
A silent mutation is a form of mutation that does not cause a significant change in the amino acid. As a result, the protein is still functional. Because of this, the changes are regarded as though they are evolutionarily neutral. Silent mutations occur in non-coding regions or within exons as opposed to the closely similar type of mutation called synonymous mutations that particularly occur within exons.