Although it isn’t very real-world practical, researchers at Cal Tech have produced a DNA-based programmable computer. Spectrum reports that the system executes programs using a set of instructions written in DNA using six bits. Like any programmable computer, this one can execute many programs, but so far they have run 21 different programs.
Using DNA for computation isn’t new — your body does it all the time. But, in general, DNA computers were akin to some logic gates that would do one set of things, not a general-purpose reprogrammable computer.
DNA has two parts composed of four different chemicals — you can think of each part as a ladder cut vertically down the middle with each “rung” being one of the four chemicals. Each part will try to pair up with a part that has a complementary set of rungs. The researchers created DNA strands to act like logic gates that have two inputs and two outputs. They combine five of these gates to create a layer with six inputs and six outputs. A program contains a stack of these six-bit layers.