Point mutations - Labster Theory - hth华体会最新网站

Point mutations are thosemutationsthat affect a single base pair. The most common nucleotide mutations are substitutions, in which one base is replaced by another. These can be of two types, either transitions or transversions. Transition substitution refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine. Transversion substitution refers to a purine being replaced by a pyrimidine, or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine.

根据不同的变化in the coding sequence the point mutations can be categorized into following three groups:

Silent mutations have no effect on the protein sequence. Missense mutations result in an amino acid substituation. Nonsense mutations lead to the substitution with a stop codon.

Cartoon of 3 types of point mutations. Silent mutation contains one nucleotide base pair change, however the same amino acid, valine, is produced. Missense mutation contains one nucleotide base pair substitution that results in one different amino acid substitution. Nonsense mutation contains one nucleotide base pair substitution that results in the production of a stop codon.