transfer RNA

Transfer RNA, or tRNA, is the courier and the adaptor of translation. Each tRNA grabs one specific amino acid at one end and carries a three-base tag, the anticodon, at the other. By matching its anticodon to a codon on the mRNA, it delivers the right amino acid to the right place in the growing protein.

This is the physical link that turns a nucleotide message into an amino-acid chain: the tRNA is the only molecule that physically connects a codon to its corresponding amino acid. A cell has a family of different tRNAs, collectively able to read all the codons of the genetic code.

Loading the correct amino acid onto each tRNA is done by dedicated enzymes (aminoacyl-tRNA synthetases) that recognize both the tRNA and its proper amino acid. This charging step is where much of translation's accuracy is decided — a tRNA carrying the wrong amino acid would silently introduce errors into the protein.