anticodonja

Anticodona (often referred to in English as anticodons) are the three-nucleotide sequences located in the anticodon loop of transfer RNA (tRNA) molecules. They recognize specific codons in messenger RNA (mRNA) during protein synthesis, guiding the insertion of the correct amino acid carried by the tRNA into the growing polypeptide chain. Each tRNA is linked to one amino acid by aminoacyl-tRNA synthetases, and the anticodon ensures proper decoding of the genetic information.

Structure and orientation: The anticodon is part of the tRNA molecule and pairs with a complementary codon on the mRNA in an antiparallel fashion. In standard representations, the anticodon is written 5' to 3' while the corresponding codon on the mRNA is read 3' to 5'. This base-pairing follows Watson–Crick rules, allowing accurate translation of the genetic code.

Function and genetic code: During translation, the ribosome accommodates the tRNA anticodon with the mRNA codon, delivering the correct amino acid. Because the genetic code is degenerate, multiple codons can code for the same amino acid; different tRNA anticodons (isoacceptors) can recognize these codons, aided by wobble base pairing at the codon-anticodon interface.

Wobble and modifications: The third base of the codon and the first base of the anticodon often exhibit wobble, enabling a single tRNA to read several related codons. Anticodons frequently contain nucleotide modifications (such as inosine or methylated bases) that expand or refine codon recognition and enhance fidelity.

Biological relevance: Anticodona are essential for accurate translation, influencing translation efficiency, codon usage adaptation, and cellular responses to stress. They are a focus in studies of genetic code evolution, tRNA biology, and related diseases.