DNA Computing

DNA is essentially the biological equivalent of information. Biotechnology is sometimes called the marriage of biology and information technology. Therefore, DNA can be used as information storage. Since biological agents can manipulate DNA, DNA can be seen as a kind of computer - much like the famous ribbon-based Turing machine. A Turing machine is a theoretical construct: Imagine a machine that processes a long ribbon of instructions and then either writes an output or not and moves to the next instruction on the ribbon. Turing showed that any computable problem could be solved by a machine with these simple functions.

DNA computing is particularly suited for combinatorial problems like the traveling salesman problem, a particularly hard-to-solve optimization problem that deals with finding the shortest route to visit some number of cities. When Adleman (1994) showed how to solve the problem for seven cities using DNA sequences, DNA computing got a big boost. The largest challenge for a DNA computing is that most calculations take place in a fluid phase by adding chemicals. This introduces hairy engineering problems, particularly if the results of the DNA computing are to feed into an ordinary silicon-based environment. In short, water and electricity don't mix. Furthermore, the DNA computer is not errorless. Thus, for particularly difficult problems, it might be worth the effort to set up a DNA computer in a wet lab, but for now this method seems ill suited for a desktop model. Perhaps, however, the application for a DNA computing will be more prosaic: to store genetic information without resorting to silicon. Adleman makes a similar point: "Whether or not DNA computers will ever become standalone competitors for electronics is besides the point. …I believe things like DNA computing, along with the other ways we are learning to use these wonderful tools, will eventually lead to a 'molecular revolution,' which ultimately will have a very dramatic effect on the world."

As if to drive that message home, in recent years some scientists have shown that computing can be conducted using DNA. This brings us full circle, for I began by suggesting that DNA provides a kind of proof-of-principle for molecular computation. But in the cell it provides the programme for making proteins. No one dreamed, until Leonard Adleman suggested it in 1994, that DNA could be used to solve the same kinds of problems as computers. Adleman realized that the genetic code can be used, just like the binary code of computer science, to encode mathematical problems. He showed that biotechnological techniques for manipulating and rearranging DNA can be used to generate all possible answers to such a problem, each one encoded in a molecule of DNA. Techniques for analyzing DNA sequences are then employed to screen through all these possible answers and identify the correct one.

By shuffling and splicing short segments of DNA at random, all the solutions to these problems may be encoded in a test tube of single-stranded DNA molecules. The number of such solutions might be huge - but the number of molecules in a test tube is greater still. And, because all the possible answers are produced and tested at once, rather than one at a time, in principle DNA computing can find the 'best' answer rapidly.

Whether or not DNA computing proves to be useful in a practical sense, it has a strong allegorical appeal. It drives home the message that the molecular basis of life is rooted in the manipulation of information. It is often said that each age tends to interpret the world through models derived from its most advanced technology, and so maybe in the Age of Information we should be wary of becoming too dogmatic about such a (partial) answer to the perennial question that haunted Haldane, Schrodinger, and countless others. It is perhaps more important that we regard this as a demonstration of the fabulously dynamic, interactive world inhabited, unseen and too often unsung, by molecules.

Order Custom Essay on DNA Computing