An anticodon, present on tRNA, is the complementary sequence to a determined codon on the mRNA. tRNA is responsible for placing the aminoacids in the correct order when a protein is being translated, and it does so by complementary binding the codons on the mRNA. Each tRNA can hold a different aminoacid, so, for example, the codon AUG encodes the aminoacid methionine, and this means that only a tRNA that has an anticodon with the sequence UAC will be able to hold metionine and place it on its position on the protein sequence.
