Scientists build a transistor from DNA In a computer, a transistor acts like a tiny switch that can be turned on or off. Computer processors, or “chips,” use hundreds of millions — and often billions — of transistors to keep information flowing. They’re used for memory, too. For example, a photograph on a memory card is saved as a series of switches in specific positions. DNA can be used to build those switches, too, say scientists who worked on the new study. They call their bio-switch a transcriptor. And it could be used with other DNA devices to build biological computers. Transistors work by controlling the flow of electricity. In one position, they let the electricity pass. In the other position, they stop the flow. A DNA switch wouldn’t affect electricity. Instead, such a device would work by either making a molecule called a protein or not.