Monday, May 27, 2002		On Hardware

Silicon is passé. How about DNA?
Jasjot Singh Narula

AN analogy is usually drawn between a computer and the human anatomy. How about the DNA (Deoxyribonucleic Acid) forming a part of the computing world?

There are million of natural supercomputers that exist in human body or living organism called DNA molecules, the material our genes are made of. They can perform millions of calculation much faster than the silicon-based microprocessor.

The computer chip manufacturers are aggressively making more powerful processors with million of transistors in a tiny little chip. Microprocessors made of silicon will eventually reach their limit of speed and shrink but what next. The DNA-based computer will be the future and this is imminent.

DNA is nucleic acid that carries the genetic information in the cell and capable of self-replication and synthesis of RNA (Ribonucleic Acid). DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between complementary bases, Adenine and Thymine or Cytosine and Guanine. The sequence of nucleotides determines individual hereditary characteristics.

The concept of DNA computing is a brainchild of Leonard Adelman. In 1994, Adelman, a computer scientist at the University of Southern California, came to the conclusion that DNA had computational potential after reading the book "Molecular Biology of the Gene", written by James Watson, who co-discovered the structure of DNA in 1953. He had used the DNA to solve complex mathematical problems called directed Hamilton Path problem, also known as the "travelling salesman problem". The main objective of the problem was to find the shortest route between a numbers of cities, going through each city only once. As you add more cities to the problem, the problem becomes more complex. Adelman chose to find the shortest route between seven cities. He took the example of a travelling salesman, frequenting various cities and created a hypothesis in a DNA test tube.

Adleman pointed out that the medium was remarkable for speed, energy efficiency and memory. Speed because it is 100 times faster than the supercomputer. DNA stores memory at a density of about 1 bit per cubic nanometer. This is about trillion times the data stored on the normal CD.

Three year after the Adleman experiment, researchers at the University of Rochester developed logic gates made of DNA. In electronic computation, logic gates are essential to convert binary data into meaningful signals for performing operations. The DNA logic gates detect specific fragments of genetic blueprint as input and join these to form output.

Scientists around the globe are now trying to marry computer technology and biology by using nature's own design to process information. Israeli scientists have built a DNA computer so tiny that a trillion of them could fit in a test tube and perform a billion operations per second with 99.8 per cent accuracy.

Gordon Moore made his famous observation in 1965, just four years after the first planar integrated circuit was discovered. The Press called it the "Moore's Law." In his original paper, Moore had predicted that the number of transistors per integrated circuit would double every 18 months. With DNA computer, this might fail.

There are several advantages of DNA computer over silicon chips; firstly they are easily available, are a cheap resource and smaller than the present day transistors in a microprocessor.

DNA-based computers are still in infancy and require a lot of research and groundwork. Once integrated into a computer chip, known as biochip, this will make computers thousand times faster that would be capable of storing billions of times more data than the present computers.

DNA computer components like logic gates and biochips takes years to develop into practical form. If built, they will be more effective than the conventional computers we are using these days. The first DNA computer will probably be equipped with word processor, e-mailing and solitaire programs. They can be used in cracking secret codes and provide simple and efficient routes to airlines.