Anticodon- Definition, Principle, Functions, Examples


An anticodon is a sequence of three nucleotides that is part of a transfer RNA (tRNA) molecule. It is complementary to a codon, which is a sequence of three nucleotides on a messenger RNA (mRNA) molecule. The anticodon and the codon pair together during the process of translation, which is the synthesis of proteins from mRNA.

The anticodon is located on one end of the tRNA molecule, called the anticodon loop or arm. The other end of the tRNA molecule has a site where a specific amino acid can attach. The amino acid is determined by the anticodon sequence, according to the genetic code. For example, the anticodon UAC corresponds to the amino acid methionine.

The function of the anticodon is to recognize and bind to the codon on the mRNA that matches its sequence. This ensures that the correct amino acid is brought to the ribosome, where the protein chain is assembled. The ribosome moves along the mRNA and reads each codon, then matches it with the appropriate tRNA anticodon. The amino acid carried by the tRNA is then added to the growing protein chain.

The pairing between the anticodon and the codon follows the rules of base complementarity: A pairs with U, and C pairs with G. However, there is some flexibility in the pairing of the third base of the anticodon, also known as the wobble position. This allows some anticodons to bind to more than one codon, which reduces the number of tRNAs needed to code for all 20 amino acids.

Some examples of anticodons and their corresponding amino acids are:

  • UAC - methionine
  • AAA - phenylalanine
  • GAA - leucine
  • CAA - valine
  • AGA - serine
  • UGA - threonine
  • CGA - alanine
  • AUA - tyrosine
  • GUA - histidine
  • UUU - lysine

In summary, an anticodon is a key component of tRNA that enables translation by pairing with codons on mRNA and delivering amino acids to the ribosome.