In the most literal interpretation of the term, biological computation refers to computation by means of biological systems — specifically, biological systems/processes that imbed mathematical/computational operations — hence, its application to the emerging subdiscipline of biology that explores and exploits the use of biological systems to perform mathematical/computational operations and achieve solutions to mathematical/computational problems — for example, computing with DNA molecules[1] — and that studies computational processes in biological and living systems.[2][3][4]
The prospect of using molecules and chemistry to undertake massively parallel computation has been raised.[5] The notion is based upon simultaneous analysis of an assembly of molecules like DNA that are "trial" solutions and use of various chemical tricks to decide in parallel which ones fit the problem criteria. A description of one such approach is provided by Maley.[6] A practical problem has proved to be a high error rate that requires careful study.
One different kind of application for biological computation is the administration of chemotherapy. The underlying idea is that bacteria are arranged to invade a tumor to selectively produce a drug that kills the tumor. Within the injected bacteria is an embedded controller that executes the logical computation "If X is present, produce Y" or possibly, "If the rate of change of X is within certain bounds, produce Y", thereby conditionally activating the bacteria only where a tumor is present.[7]