Anticodon

Definition

A three-nucleotide sequence in a transfer RNA (tRNA) molecule that is complementary to a specific codon in messenger RNA (mRNA). During translation at the ribosome, the anticodon forms base pairs with its matching mRNA codon, ensuring the correct amino acid is inserted into the growing polypeptide chain according to the genetic code.

Etymology

From Greek anti- (against, opposite) + codon (a code unit), reflecting its complementary pairing function with mRNA codons.

Example

In the honey bee (Apis mellifera), a tRNA carrying the amino acid phenylalanine possesses the anticodon 3'-AAG-5', which recognizes and binds to the mRNA codon 5'-UUC-3' during synthesis of royal jelly proteins in the hypopharyngeal glands.

Related Terms

• Codon
• transfer RNA
• messenger RNA
• translation
• Ribosome
• wobble base pairing
• Genetic code

Usage Notes

Anticodons are written 5' to 3' or 3' to 5' depending on convention; the actual binding is antiparallel. The first anticodon position (the 'wobble' position) often tolerates non-Watson-Crick pairing, allowing one tRNA to recognize multiple codons. In arthropod molecular studies, anticodon mutations in mitochondrial tRNAs are frequently implicated in metabolic disorders and population fitness variation.