The transfer RNA, (tRNA) molecule of a cell acts as a vehicle that picks up the amino acids scattered through the cytoplasm and also reads specific codes of mRNA molecules. Hence it is called an adapter molecule.
The clover leaf model of tRNA shows the presence of three arms namely DHU arm, middle arm and TΨC arm. These arms have loops such as amino acyl binding loop, anticodon loop and ribosomal binding loop at their ends. The amino acid is attached to one end (amino acid acceptor end) and the other end consists of three anticodon nucleotides. The anticodon pairs with a codon in mRNA ensuring that the correct amino acid is incorporated into the growing polypeptide chain.
The process of addition of amino acid to tRNA is known as aminoacylation or charging and the resultant product is called aminoacyl- tRNA (charged tRNA). This aminoacylation is catalyzed by an enzyme aminoacyl – tRNA synthetase.
The tRNA charged with amino acid serves as an adapter molecule to decode the information on mRNA. This is achieved by the interaction of tRNA with mRNA. The tRNA molecule has a region that contains complementary bases (anticodon) to the codon on the mRNA.