Protein synthesis. Computer illustration showing how proteins are synthesised from amino acids (coloured spheres) within a cell. Proteins are synthesised according to the information carried in segments of a DNA (deoxyribonucleic acid) strand (upper left) known as genes. A strand of messenger ribonucleic acid (mRNA) is copied from the DNA strand in the nucleus (left) and moves to a ribosome (beige, centre-right). Short strands of transfer RNA (tRNA, bell-shaped) then transport the corresponding amino acids to the ribosome, where they are assembled into a protein chain (upper centre) according to the sequence encoded by the mRNA strand.