Transfer RNA, or tRNA, plays a vital role in the synthesis of proteins inside the cell by transcribing messenger RNA and attaching amino acids to form a chain. This process gradually builds up the long chains of amino acids required to build proteins.
Protein synthesis begins deep inside the cell nucleus. There, a special type of catalyst called messenger RNA reads the pattern of instructions coded into the DNA. mRNA does this by pressing itself against the DNA sequence it is reading and bending into a negative impression of the gene on that section of DNA. The mRNA holds this shape as it passes out of the nucleus and onto the surface of the cell's golgi apparatus, which is a large, folded membrane extending outward from the nucleus. Once there, the mRNA comes into contact with tRNA, which begins transcribing the pattern encoded on the mRNA.
Units of tRNA are shaped almost like three-leaf clovers, with multiple hairpin loops at the end of long ribosomal arms. Each loop contains an amino acid, which the tRNA inserts into the growing chain in response to changes in the mRNA's shape. As the tRNA deposits amino acids, the chain grows until it can be released, at which point it snaps into shape as a protein.