Analysing a protein purity profile. Biotechnologists looking at a protein purity profile of recombinant proteins. Recombinant proteins are a product of genetic engineering, as the DNA (deoxyribonucleic acid) that produces these proteins has been modified from its original form. For example the DNA in some bacteria can be engineered to make human proteins such as insulin, an enzyme needed by diabetics who cannot produce their own to regulate their blood sugar. Photographed at the National Physical Laboratory in Teddington, UK.