Translation unit from a salivary gland cell of a midge (Chironomus sp.), coloured transmission electron micrograph (TEM). Translation is the synthesis of proteins from a messenger ribonucleic acid (RNA) strand. mRNA consists of groups of three nucleotide bases that code for different amino acids, the building blocks of proteins. Ribosomes (yellow) attach to the mRNA strand and read its code. A transfer RNA (tRNA) molecule carrying an amino acid corresponding to the code attaches to the ribosome. When the tRNA dissociates it leaves the amino acid, and the ribosome moves onto the next bases. The amino acids left behind form a growing protein chain.