Computer Science

In today’s world, humans are very dependent on computers and are relying on computer technology to keep increasing at the rate it is. Soon microprocessors made of silicon will reach their limits of speed and miniaturization. Silicon based computers will become obsolete and a replacement will be needed. DNA computers are the replacement.

Chipmakers need a new material to produce faster computing speed with complexities. DNA, the material our genes are made of, is being used to build the next generation of microprocessors. Scientists are using DNA to create a new breed of biologically based bacterial nano-computers of the future which may have the capacity to impact and alter desktop computing forever, through miniaturization that could bring huge increases of computing capacity, power, storage and speed.

A nascent technology that uses DNA molecules to build computers that are faster than the world’s most powerful human-built computers is called DNA computing.DNA computing also known as molecular computing is a new approach to massively parallel computation based on groundbreaking work by Adleman.

DNA computers have emerged as an indisciplinary field that draws together molecular biology, chemistry, computer science and mathematics. A DNA computer is basically a collection of specially selected DNA strands whose combinations will result in the solution to some problems. Technology is currently available both to select the initial strands and to filter the final solution. DNA computation is a new computational paradigm that employs bio-molecular manipulation to solve computational problems. In 1994, Leonard Adleman at the Laboratory of Molecular Science, Department of Computer Science, University of Southern California surprised the scientific community by using the tools of molecular biology to solve different computational problems. The main idea was the encoding of data in DNA strands and the use of tools from molecular biology to execute computational operations. Besides the novelty of this approach, DNA computing has the potential to outperform electronic computers. There are two main reasons for using molecular biology to solve computational problems.

• The information density of DNA is much greater than that of silicon:
1 bit can be stored in approximately 1 cubic nanometer. Other storage devices like videotapes can store 1 bit in 1000 000 000 000 cubic nanometer.

• Operations on DNA are massively parallel:
A test tube of DNA contains trillions of strands. Each operation is carried out in all strands in the tube in parallel.

DNA computing is a novel technology that seeks to capitalize on the enormous capacity of DNA, biological molecules that can store huge amounts of information and are able to perform operations similar to that of a computer, through the deployment of enzymes, biological catalysts that act like software to execute desired operations. DNA computing brings greater optimization to revolutionize the computer industry in the use of molecules of DNA in a computer, in place of electronics, circuits and magnetic or optical storage media. For serial logic, DNA computers are not a viable option. However for parallel logic, a DNA computer can perform 1014 million instructions per second. It also requires less energy and space. The computing power of a teardrop sized DNA computer will be more powerful than the world’s most powerful super computer.

DNA is the basic component of DNA computers. Instead of using electrical impulses to represent bits of information, the DNA computer uses the chemical properties of these molecules by examining the patterns of combinations or growth of the molecules. DNA can do this through the manufacture of enzymes, which are biological catalysts that could be called the software used to execute the desired calculation. In DNA computers data are entered and coded into DNA by chemical reactions and retrieved by synthesizing a key data and make them react with existing DNA strands. Here the key DNA will stick to the required DNA strands containing data. In short, in a DNA computer, the input and output are both strands of DNA. A single strand of DNA is similar to a string consisting symbols A, G, C, T. Mathematically, this means we have a set, E={A, G, C, T} to encode information which is more than enough considering that an electronic computer needs only two digits and for the same purpose. In DNA computer, the input and output are both strands of DNA, whose genetic sequences encode certain information. A program on a DNA computer is executed as a series of biochemical operations, which have the effect of synthesizing, extracting, modifying and cloning the DNA strands.

DNA computers will work through the use of DNA based logic gates. These logic gates are very much similar to what is used in our computers today with the only difference being the composition of input and output signals. In the current technology of logic gates, binary codes from the silicon transistors are converted into instructions that can be carried out by the computer. DNA computers on the other hand, use DNA codes in place of electrical signals as input to DNA logic gates. They detect fragments of genetic material as input, splice together these fragments and form a single output. For instance, a genetic gate called ‘AND gate’ links two DNA inputs by chemically binding them so that they are locked in an end-to-end structure.
The ability to build a biochip lies first and foremost in the ability to merge the biological parts with the electronics into hybrid systems. MEMS- Micro Electro Mechanical System is the practice of combining miniaturized mechanical and electronic components. Any successful biochip can be built by combining the latest electronic technologies. Successful MEMS technology will be the key to building biochips. One advantage of biochip is that its manufacture does not produce any toxic by-products.

DNA computing is in its infancy and its implications are only beginning to be explored. But DNA computing device could revolutionize pharmaceutical and biomedical fields. The first DNA computers are unlikely to feature word processing, e-mailing and solitaire programs. Instead their enormous computing power will be used by national governments for cracking secret codes or by airlines wanting to map more efficient routes. Studying DNA computing may also lead us to a better understanding of a more complex computer – the human brain. It can also be a general purpose tool for a variety of problems. The concept of using DNA computing in the fields of steganography, cryptography and authentication has been identified as a possible technology that may bring forward a new hope for unbreakable algorithms in the world of information security. Its applications include molecular barcode, fuzzy logic, evaluating gene sequence, selective cell treatment, ‘doctor in a cell’, genomic analysis, DNA fingerprinting etc.