= Translation
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{wiki}
= Biological translation
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<Biological translation> uses a <ribosome> to read <messenger RNA> <codons> $5'\to3'$ and assemble the corresponding <amino acid> chain. <Transfer RNA> adaptors match <codons> through <base pairing> and carry the <amino acids>; the <genetic code> supplies the correspondence. The chain grows from the <N-terminus> toward the <C-terminus>, by adding each new residue at the <C-terminus>. See https://openstax.org/books/biology-2e/pages/15-5-ribosomes-and-protein-synthesis[Clark, Douglas and Choi, Biology 2e: ribosomes, transfer RNA and protein synthesis].
In the <gene expression> diagram, read $5'\text{-}\mathrm{AUG\ GCU\ UAA}\text{-}3'$ in the chosen <reading frame>. Under the standard <genetic code>, AUG specifies <methionine> and GCU specifies <alanine>; UAA is a <stop codon>. The result before any subsequent processing is the two-residue chain N–<methionine>–<alanine>–C, followed by termination. The <stop codon> contributes zero <amino acids>. See https://openstax.org/books/biology-2e/pages/15-1-the-genetic-code[Clark, Douglas and Choi, Biology 2e: the standard genetic code]. This example assumes appropriate initiation at the displayed AUG in a suitable context in a <eukaryote>; the diagram displays the coding segment, not a complete independently translatable <messenger RNA>.
Initiation establishes the starting position and <reading frame>, using a <ribosome>, an initiating <transfer RNA> and additional factors. At a standard <stop codon>, a release factor promotes release of the chain rather than delivery of another <amino acid> by <transfer RNA>. See https://openstax.org/books/biology-2e/pages/15-5-ribosomes-and-protein-synthesis[Clark, Douglas and Choi: initiation and termination of translation]. A short two-residue example illustrates decoding, not the size or folding of a typical functional <protein>.
The useful connection is between two different alphabets: <nucleotides> specify the order of <amino acids> through the <genetic code>. <Base pairing> helps select <transfer RNA>, while the <ribosome> catalyzes joining the delivered <amino acids>. The <messenger RNA> remains a template rather than being consumed as the chain's building material. Separating template, adaptor and product makes clear why <transcription> and <biological translation> are distinct mechanisms.
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