nonsense mutation A mutation that alters a gene so that a nonsense codon is inserted. Such a codon is one for which no normal t-RNA molecule exists: the codon therefore does not code for an amino acid. Usually a nonsense codon causes the termination of translation (i.e. the end of the polypeptide chain). Three nonsense codons are recognized, and are called the amber, ochre, and opal codons.

nonsense mutation A mutation that alters a gene so that a nonsense codon is inserted. Such a codon is one for which no normal t-RNA molecule exists; the codon therefore does not code for an amino acid. Usually a nonsense codon causes the termination of translation (i.e. the end of the polypeptide chain). Three nonsense codons are recognized, and are called the amber, ochre, and opal codons.

nonsense mutation A type of point mutation that converts a codon normally specifying an amino acid to one of the stop codons, thus signalling termination of translation and causing synthesis of the polypeptide chain to cease prematurely.

nonsense mutation A mutation which results in a nonsense codon.