Biological computing is a young field which attempts to extract computing power from the collective action of large numbers of biological molecules. One can think of a biological computer as a massively parallel machine where each processor consists of a single biological macromolecule. By employing extremely large numbers of such macromolecules in parallel, one can hope to solve computational problems more quickly than the fastest conventional supercomputers. The most promising proposals so far for biological computers involve the very same molecule that encodes our own genetic identity, namely deoxyribonucleic acid (DNA).

The first proposal for a biological computer was made by Leonard Adleman in 1994. Adleman showed how to use DNA to solve the NP-complete Directed Hamiltonian Path (DHP) problem in graph theory. In order to explain this seminal work, we first discuss relevant information about DNA from the field of molecular biology. A strand of DNA...