The function of tRNA is to decode an mRNA sequence into a protein and transfer that protein to the ribosomes where DNA is replicated. The tRNA decides what amino acid is needed according to the codon from the mRNA molecule. Then the tRNA molecule attaches the amino acid to the amino acid chain and returns to the cytoplasm to do it all over again.
The tRNA molecule, or transfer ribonucleic acid molecule, has two specific functions. According to Scitable, its first function is a translator. It decides what amino acid is needed by looking at the mRNA. The mRNA molecule has three nucleotides, or codons, that refer to a specific amino acid. Once the tRNA molecule recognizes the particular amino acid it needs, its second function kicks in and it becomes a transferrer, moving that amino acid into the growing chain of amino acids.
According to How Stuff Works, tRNA comes in 20 different kinds of molecules, each acting as a carrier for a specific amino acid, of which there are also 20 different kinds. Each folded tRNA molecule contains an anticodon, which corresponds to a codon and determines what amino acid is needed. The tRNA molecules repeat this process until the enzyme chain is complete.