Computer Made From DNA And Enzymes

develop writes "Some folks from Israel have created a computer that runs on DNA and enzymes and is supposedly 100,000 times faster then today's PCs. Information at National Geographic, Telegraph UK and United Press." According to the National Geographic story, this DNA-based computer "can perform 330 trillion operations per second, more than 100,000 times the speed of the fastest PC." However, be aware that most of this is still future tense, and what these researchers have now is just a proof-of-concept.

Comments

Misconceptions about DNA computers

[preternatural]

There are several misconceptions about DNA computers out there that I would like to clear up. The National Geographic article was written for a popular audience and has mistakes that most of you problably picked up (for example, the beautiful quote "fuzzy logic" problems ... have many possible solutions rather than the either/or logic of binary computers). And I'm not even going to comment on the Guiness Book of World Records nonsense.

As many of you have pointed out, DNA computers are not going to replace conventional electronic computers. Len Adleman, the inventor of DNA computing, has said "Despite our successes, and those of others, in the absence of technical breakthroughs, optimism regarding the creation of a molecular computer capable of competing with electronic computers on classical computational problems is not warranted." The problem is partly the effort required to read the answer once the solution is available, and partly the effort required to perform the computation itself. Reading the answer from the first DNA computation took Adleman about a week, and reading the answer from his most recent DNA computation (the largest computation ever performed) took two weeks. The computation itself was very manpower intensive: thousands of precise moves were required of a human experimentor to get the necessary components in a test tube, but once they were all in, the computation itself happened virtually instantly.

Although I have only read the popular accounts of this experiment and not the actual results, this experiment seems to simply be using the ATP in DNA as the power source for the computation instead of external ATP. This is impressive, but it is not the "technical breakthrough" needed to propel DNA computing to the everyday world.

The claim of this computer working 100,000 times faster than a PC is probably true. But this speed comes from the parallelism inherint in DNA computation. When each computer is only 1 molecule in size, it is easy to have 10^10 computers in one tube. But if you do the math, this says that each individual molecule is 100,000 times slower than a PC. So it is equally true to say that my PC is 100,000 times faster than a DNA computer, its just that I can't afford millions of them. This also says that DNA computers are not good for computations that are serial in nature: the speed comes from the fact that DNA computers can run in parallel.

That being said, there may be specific applications for DNA computers in the future. Because of their parallelism, DNA computers are great at solving NP-complete problems (not fuzzy logic problems, as said in the article). This does not make them tractable, however. They run in linear time, but take exponential space. So instead of the problem that "solving this problem will take the age of the universe" you run into the problem "solving this problem will require the mass of the Earth in DNA".