DNA COMPUTERS

Israeli scientists have devised a computer composed of DNA and enzymes. The enzyme FokI breaks bonds in the DNA double helix, causing the release of enough energy for the system to be self-sufficient. It runs on DNA. As of now, the DNA computer can only perform rudimentary functions, and it has no practical applications. The device can check whether a list of zeros and ones has an even number of ones. The computer cannot count how many ones are in a list, since it has a finite memory and the number of ones might exceed its memory size. It can only answer yes or no to a question. It can't correct a misspelled word. In terms of speed and size, however, DNA computers surpass conventional computers. While scientists say silicon chips cannot be scaled down much further, the DNA molecule found in the nucleus of all cells can hold more information in a cubic centimeter than a trillion music CDs. A spoonful of Shapiro's "computer soup" contains 15,000 trillion computers. And its energy-efficiency is more than a million times that of a PC.