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Silent mutations, also called synonymous or samesense mutations, ... This is an example of how some silent mutations are not always silent. [25]
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.
These are both examples of a non-conservative (missense) mutation. Silent mutations code for the same amino acid (a "synonymous substitution"). A silent mutation does not affect the functioning of the protein. A single nucleotide can change, but the new codon specifies the same amino acid, resulting in an unmutated protein.
Not all missense mutations lead to appreciable protein changes. An amino acid may be replaced by an amino acid of very similar chemical properties, in which case, the protein may still function normally; this is termed a neutral, "quiet", "silent" or conservative mutation.
An example would be a seemingly silent mutation in the multidrug resistance gene 1 , which codes for a cellular membrane pump that expels drugs from the cell, can slow down translation and allow the peptide chain to fold into an unusual conformation, causing the mutant pump to be less functional (in MDR1 protein e.g. C1236T polymorphism changes ...
Many mutations are silent mutations, causing no visible effects at all, either because they occur in non-coding or non-functional sequences, or they do not change the amino-acid sequence due to the redundancy of codons. [33] Some mutagens can cause aneuploidy and change the number of chromosomes in the cell. They are known as aneuploidogens. [34]
What is the bird flu pandemic risk? CDC analysis suggests the H5N1 virus has the capacity to mutate in ways that could make it more transmissible to humans.
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.