tRNA stands for transfer-RNA which is used in the process of protein synthesis or translation. tRNA is a unique clover leaf like structure that has 4 arms- amino acid acceptor site (acceptor arm), D loop, T psi C loop and anticodon loop. It also has a small variable loop. The anticodon loop consists of a sequence of 3 bases that is complementary to the 3 bases present of mRNA to be translated. A tRNA for alanine will have an anticodon for alanine while a tRNA for lysine will have an anticodon for lysine. For a tRNA to insert an alanine in place of lysine in a forming peptide, the anticodon and the amino acid acceptor site should be altered so that it accepts lysine in place of alanine and add it to the growing polypeptide.