Scientists in Israel have developed what amounts to the world's first biological computer – a diminutive combination of enzymes and DNA molecules that can be programmed to make simple calculations. The biological computer is so small that some would argue whether or not it should be called a computer at all. Whatever the case may be, billions of the tiny mites are said to fit nicely in a drop of water.

As far as what practical use the biological computer could have for mankind, its developers are predicting a day when it will monitor abnormal biological changes in the body and respond to these changes by synthesizing and releasing drugs to instantly treat the condition. That day may still be a long way off, however, as these simple machines currently only have the ability to make basic computations. As Ehud Shapiro, research director at the Weizmann Institute of Science, explains, "It is a computer, but not a general purpose, universal computer. What we have implemented is the simplest, non-trivial, finite automaton, which has only two states and an alphabet of only two symbols. It can answer only simple questions."

This simple mathematical computing machine, or "finite automaton," uses two naturally occurring enzymes that can manipulate DNA as its "hardware." The "software" and "hardware" molecules, when mixed in a solution, operate in harmony on what is known as an "input" molecule. The computer can then be programmed to perform simple tasks by choosing different "software" molecules to be mixed in solution.

Though the questions the biological computer can handle are very simple, such as determining whether the number of times a symbol occurs in a particular binary code is an odd or even number, it does so very quickly: a billion per second reportedly. Due to its speediness, the biological computer may find its most immediate use helping scientists accelerate the study of DNA. It could do this by forming the basis of computers capable of screening DNA libraries in parallel, without sequencing each molecule as it is required currently. According to Shapiro, "Such machines might analyze natural DNA, human or otherwise, in the lab within a few years." About the biological computer's future as an interior medical device, Shapiro adds, "The time when such machines can actually operate within the human body, programmed with medical knowledge so that they can effect some medical treatment at the molecular level, is at least a few decades away."

Source: Nanotech: A Billion Computers in a Drop of Water
Tim McDonald
NewsFactor Network, December 5, 2001
http://www.newsfactor.com/perl/story/?id=15100