tRNA is a relatively small molecule of around 80 nucleotides that is a single strand folded into a clover leaf shape by hydrogen bonding between bases.One end of the tRNA molecule extends beyond the other and this acts as an amino-acid binding site. Each tRNA molecule binds a different amino acid with an ester bond.At the other end three bases form the anticodon which is complementary to a codon on mRNA and temporarily binds to mRNA with hydrogen bonds. Uracil binds with adenine forming two hydrogen bonds and cytosine binds with guanine forming three hydrogen bonds. This is known as complementary base-pairing.The binding of the codon and anticodon is also by complementary base pairing.