DNA Computers

The latest computer to come out of the University of Southern California isn’t newsworthy for its small size or computational power. It’s notable because it is made from DNA, the microscopic acids that reside in every cell and are responsible for all life. The DNA computer, which more closely resembles a biochemistry lab than a PC, was the first nonelectronic device?including the human mind?to solve a logic problem with more than 1 million possible answers.

Len Adleman, the USC professor who led the research, says that DNA is actually quite similar to binary code. Each DNA strand is made up of some combination of A’s, T’s, C’s and G’s that act just like a computer’s 1’s and 0’s. Furthermore, DNA copies, stores and parses information like a human hard drive and processor. “Inside the cell you have all the basic tools,” says Adleman. “It’s just a matter of carrying out the computation.”

The problem Adleman’s DNA computer solved involved 20 variables. For example, John wants a car that is red, has a sunroof, four-wheel drive and so on. Adleman’s team coded strands of DNA with all the possible answers and then subjected the strands to a series of steps that eliminated ones with incorrect answers until only the strand with the correct answer remained. All in all, it took about two days. On a traditional computer, Adleman says, “that problem would take less than a second. Electronic computers transcended that [kind of problem] 50 years ago.”

While the experiment convinced Adleman that DNA computers will never be able to rival their electronic counterparts for speed without an unforeseen scientific breakthrough, he does think that they have a future niche. One day, a DNA computer programmed to react to the presence of a toxin, such as cancer, could be embedded into a cell. When it detects the toxin, the computer would respond by directing the cell to replicate and chemoluminesce or “glow.” The glow could be seen with the naked eye allowing for early disease detection and saving lives. Let’s see a ThinkPad do that.