Cellular protein synthesis by ribosomes. Illustration of the inside of a cell, showing proteins (one see as a green strand after elongation at upper right) being synthesized by ribosomes (large structure at upper right). The instructions for building the proteins are encoded in strands of messenger ribonucleic acid (mRNA, multi-coloured strands) that originate in the cell nucleus (left), and is a copy of the information coded in DNA (deoxyribonucleic acid) in the nucleus. The mRNA is shown emerging from nuclear pores. Transfer RNA (red) brings amino acids (green) to a ribosome, where they are joined in a sequence determined by the mRNA. Different sequences produce different proteins.