Genetic code: Difference between revisions

Revision as of 18:10, 25 October 2001

Revision as of 23:53, 25 October 2001

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The genetic code is a translation table for how triplets of adjacent [[nucleotide|bases]], called ''[[codon|codons]]'', specify [[amino acid]]s in [[protein]] biosynthesis. In this process, the bases in the [[DNA]] from a gene are first copied into a molecule of [[mRNA]] during [[transcription]], certain sections of the [[mRNA]] are spliced out, and then amino acids are linked to it by molecules of [[tRNA]] during [[translation]]. Some codons do not specify an amino acid, called STOP codons, which as a result end the translation process.

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In classical genetics, the STOP codons were given names - UAG was amber, UGA was opal, and UAA was ocher. These names were originally the names of the specific genes in which mutation of each of these stop codons was first detected. Translation starts with a chain initiation or START codon, but unlike STOP codons these are not sufficient by themselves to begin the process; nearby initiation sequences are also required to induce transcription into mRNA and binding by ribosomes[[ribosome]]s. The most notable of these is AUG, which also codes for methionine. CUG and UUG, and in prokaryotes GUG and AUU, will also work.