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Why can several different codons specify the same amino acid?
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Amino acid
The structure and function of amino acids.
The genetic code is described as degenerate because most of the 20 amino acids are specified by more than one codon. While there are 64 possible triplet combinations of the four nitrogenous bases, only 61 of these codons encode amino acids, while three serve as stop signals to terminate protein synthesis.12
Because there are more available codons than there are amino acids, the system naturally allows for multiple codons to correspond to the same amino acid. For instance, while methionine and tryptophan are each specified by only a single codon, other amino acids—such as serine and leucine—can be coded for by as many as six different codons. This redundancy is a fundamental feature of the genetic code across almost all living organisms.3124