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A nonsynonymous substitution is a nucleotide mutation that alters the amino acid sequence of a protein. Nonsynonymous substitutions differ from synonymous substitutions , which do not alter amino acid sequences and are (sometimes) silent mutations .
Missense mutation is a type of nonsynonymous substitution in a DNA sequence. Two other types of nonsynonymous substitution are the nonsense mutations , in which a codon is changed to a premature stop codon that results in truncation of the resulting protein , and the nonstop mutations , in which a stop codon erasement results in a longer ...
Amino acid replacement is a change from one amino acid to a different amino acid in a protein due to point mutation in the corresponding DNA sequence. It is caused by nonsynonymous missense mutation which changes the codon sequence to code other amino acid instead of the original. Notable mutations
Nonsynonymous substitutions can be classified as nonsense or missense mutations: ... Conditional mutation is a mutation that has wild-type (or less severe) ...
Silent mutations, also called synonymous or samesense mutations, are mutations in DNA that do not have an observable effect on the organism's phenotype. The phrase silent mutation is often used interchangeably with the phrase synonymous mutation ; however, synonymous mutations are not always silent, nor vice versa.
It is calculated as the ratio of the number of nonsynonymous substitutions per non-synonymous site (K a), in a given period of time, to the number of synonymous substitutions per synonymous site (K s), in the same period. The latter are assumed to be neutral, so that the ratio indicates the net balance between deleterious and beneficial mutations.
Missense mutations differ from nonsense mutations since they are point mutations that exhibit a single nucleotide change to cause substitution of a different amino acid. A nonsense mutation also differs from a nonstop mutation , which is a point mutation that removes a stop codon.
Point substitution mutations of a codon, classified by their impact on protein sequence. A synonymous substitution (often called a silent substitution though they are not always silent) is the evolutionary substitution of one base for another in an exon of a gene coding for a protein, such that the produced amino acid sequence is not modified.