Protein assembly

Once in the cytoplasm, the mRNA is snatched up by tiny protein-assembly machines called ribosomes. Each ribosome works its way along the mRNA, reading the code from 'start' to 'stop', selecting the correct amino acid building blocks and ejecting a growing protein. It takes just one 50th of a second for the ribosome to select and add each building block. At this rate, a cell can assemble a small protein like insulin in just a few seconds.