DNA Computing
Posted: Tuesday, June 21, 2005
by Dayana
auto">DNA Computing
DNA (deoxyribonucleic acid) molecules, the material our genes are made of, have the potential to perform calculations many times faster than the world's most powerful human-built computers. DNA might one day be integrated into a computer chip to create a so-called biochip that will push computers even faster. DNA molecules have already been harnessed to perform complex mathematical problems.
The main benefit of using DNA computers to solve complex problems is that different possible solutions are created all at once. This is known as parallel processing. Humans and most electronic computers must attempt to solve the problem one process at a time (linear processing). DNA itself provides the added benefits of being a cheap, energy-efficient resource.
Take for example, problems involving finding many possible solutions and then finding the correct one. Since a standard computer can only generate a possible solution one-at-a-time, and check possible solutions one-at-a-time, problems such as these get increasingly more complex for these one-at-a-time computers as the number of possibilities rises. In DNA computing, a DNA strand can be replicated 500 times a second (this is pretty fast, considering the 99.8% accuracy rate in DNA replication because the bases A, T, G, and C pair up to create a sort of "backup" to one DNA strand in case there is a mistake. If many enzymes (enzymes have jobs that are similar to commands on a computer, cutting, pasting, replicating, repairing DNA strands) are allowed to work on DNA in parallel, they can start working on the second strand before the first is completely copied, and so on, increasing the data path about 1000 bits per DNA strand. And since the DNA strands increase exponentially, you soon have data paths of thousands of gigabytes, much bigger than any modern computer today.
Data density in DNA is also hugely bigger than standard computers. A DNA strand has the bases A, T, C, and G spaced evenly 0.35 nanometers apart on it. This means that, if there is one base per square nanometer, the data density of one square inch is close to a million gigabytes. In a standard computer, data density is close to 100,000 times smaller, around 7 gigabytes per square inch.
In a different perspective, more than 10 trillion DNA molecules can fit into an area no larger than 1 cubic centimeter. With this, a DNA computer could hold 10 terabytes of data and perform 10 trillion calculations at a time.
Increasing performance is different for both types of methods. For standard computers, increasing performance means increasing the RAM or clock-speed, so that individual tasks can be completed faster. For parallel (here DNA) computing, more memory and parallel processing increases performance.
Adleman is often called the inventor of DNA computers .He used his computer to solve the classic "traveling salesman" mathematical problem -- how a salesman can visit a given number of cities without passing through any city twice -- by exploiting the predictability of how DNA interacts.
You could probably draw this problem out on paper and come to a solution faster than Adleman did using his DNA test-tube computer. Here are the steps taken in the Adleman DNA computer experiment:
- Strands of DNA represent the seven cities. In genes, genetic coding is represented by the letters A, T, C and G. Some sequence of these four letters represented each city and possible flight path.
- These molecules are then mixed in a test tube, with some of these DNA strands sticking together. A chain of these strands represents a possible answer.
- Within a few seconds, all of the possible combinations of DNA strands, which represent answers, are created in the test tube.
- Adleman eliminates the wrong molecules through chemical reactions, which leaves behind only the flight paths that connect all seven cities.
Thus from the hodgepodge of connected DNA, Adleman eventually extracted a satisfactory solution -- a strand that led directly from the first city to the last, without retracing any steps. DNA computing was born.
New computers made of biological molecules that react to DNA hold the promise to diagnose and treat diseases such as cancer by operating like doctors inside the body, Israeli scientists said.
The devices, used in test-tube experiments, already have demonstrated the ability to identify and then destroy prostate and lung cancer cells, but their creators cautioned it could be decades before such biological computers find their way into medicine.
As you have hopefully seen on the previous pages, DNA Computing can be used to solve problems now, problems of a type that some supercomputers have difficulty with. The best possible hope for DNA computers at this time is in devices that operate on the nanoscale level, almost infinitesimally smaller than computers of the day operate at. Possible nanodevices that could employ DNA computing technology are devices that can make repairs on the cellular level in a human body, something that current devices cannot do, and devices that act as biosensors in a human body to alert scientists or doctors when something goes wrong. DNA computing may also be used in place of silicon chips, resulting in much smaller computers.
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Top-level comments on this article: (2 total)
» left by Dick
from Dallas 6 years 229 days ago.
Good.Gives a brief idea about this new technology
» left by Dan
from US 6 years 215 days ago.
Very good.Simple and understandable.
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