When engineers need to create a novel product, these principles are applied for almost every device or machine one wants to produce, be it an airplane or a fridge. This sounds rather simplistic, but such structured, rational strategies were until recently not generally followed by experimental biologists, not even in those applications utilising "genetic engineering" schemes. Synthetic biology has pioneered the applications of such principles for the successful engineering of relatively complex synthetic switches, metabolic and signalling networks. Despite its young age it already revolutionised molecular and cellular biology research, biomedicine and the bulk-chemical and biopharmaceutical industries .