Genetic circuit diagram. Genetic circuits are used by synthetic biologists to design genetically modified bacteria cells. Synthetic biology uses standard DNA fragments known as BioBricks to program cells in the same way that electronic circuits or computer networks are designed. In this diagram, the BioBricks (represented by numbers within the red and black boxes) include triggers, switches, response and attract mechanisms. When assembled they allow bacteria to perform specific tasks. Synthetic biology may one day be used to create new drugs and biosensors and to diagnose diseases, or used to develop biological computers.