Adleman

Today’s computers are millions of times more powerful than their crude ancestors in the 40’s and 50’s. Almost every two years, computers have become twice as fast whereas their components have assumed only half the space. One of the recently introduced unconventional paradigms, which promises to have a tremendous influence on the theoretical and practical progress of computer science is DNA computing. . The concept of DNA computing was born in 1993, when Professor Leonard Adleman, a mathematician specializing in computer science and cryptography at the Laboratory of Molecular Science, Department of Computer Science, University of Southern California accidentally stumbled upon the similarities between conventional computers and DNA while reading the book “Molecular Biology of the Gene,” written by James Watson, who co-discovered the structure of DNA in 1953. Adleman came to the conclusion that DNA had computational potential to solve complex mathematical problems. In 1994, Leonard Adleman introduced the idea of using DNA to solve complex mathematical problems. In fact, DNA is very similar to a computer hard drive in how it stores permanent information about your genes.

 

WHAT IS DNA?

DNA is the master molecule of every cell. It contains vital information that gets passed on to each successive generation. It coordinates the making of itself as well as other molecules (proteins). If it is changed slightly, serious consequences may result. If it is destroyed beyond repair, the cell dies.Changes in the DNA of cells in multicellular organisms produce variations in the characteristics of a species. .DNA is one of the nucleic acids, information-containing molecules in the cell (ribonucleic acid, or RNA, is the other nucleic acid). DNA is found in the nucleus of every human cell.The information in DNA:

* guides the cell (along with RNA) in making new proteins that determine all of our biological traits

* gets passed (copied) from one generation to the next

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WHAT IS DNA COMPUTING

A DNA computer, as the name implies, uses DNA strands to store information and taps the recombinative properties of DNA to perform operations. A small test tube of DNA strands suspended in a solution could yield millions to billions of simultaneous interactions at speeds — in theory — faster than today’s fastest supercomputers.DNA computer uses the recombinative property of dna to perform operations.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 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.In a different perspective, more than 10 trillion DNA molecules can fit into an area no larger than 1 cubic  centimetre. With this, a DNA computer could hold 10 terabytes of data and perform 10 trillion calculations at a time.

COMPARISON WITH CONVENTIONAL COMPUTERS

DNA’s key advantage is that it will make computers smaller than any computer that has come before them, while at the same time holding more data. One pound of DNA has the capacity to store more information than all the electronic computers ever built; and the computing power of a teardrop-sized DNA computer, using the DNA logic gates, will be more powerful than the world’s most powerful supercomputer.More than 10 trillion DNA molecules can fit into an area no larger than 1 cubic entimetre (0.06 cubic inches). With this small amount of DNA, a computer would be able to hold 10 terabytes of data, and perform 10 trillion calculations at a time. By adding more DNA, more calculations could be performed.Unlike conventional computers, DNA computers perform calculations parallel to other calculations.Conventional computers operate linearly, taking on tasks one at a time. It is parallel computing that allows DNA to solve complex mathematical problems in hours, whereas it might take electrical computers hundreds of years to complete them.The first DNA computers are unlikely to feature word processing, e-mailing and solitaire programs.Instead, their powerful computing power will be used by national governments for cracking secret codes, or by airlines wanting to map more efficient routes. Studying DNA computers may also lead us to a better understanding of a more complex computer – the human brain.DNA computers will be capable of storing billions of times more data (say, at a density of 1 bit per cubic nanometer – a trillion times less space) than your personal computer. The DNA computer has very low energy consumption, so if it is put inside the cell it would not require much energy to work. Using DNA logic gates the DNA computers will be more powerful than the world’s most powerful supercomputer. DNA computers perform calculations parallel to other calculations.

  • Speed :Combining DNA strands as demonstrated by Dr Adleman, made computations equivalent to 10^9 or better,arguably over 100 times faster than fastest computer.
  • Minimal storage requirements: DNA stores memory at a density of about one bit per cubic nanometer where conventional storage media requires 10^12 cubic nanometers to storage one bit.
  • Minimal power requirements :No power is required for DNA computing while computation is taking place. The chemical bondsthat are the building blocks of DNA happen without any outside power source.

ADVANTAGES

  • Perform millions of operations simultaneously (Parallel Computing).
  • Generate a complete set of potential solutions and conduct large parallel searches.
  • Capable of storing billions of times more data
  • Over 100 times faster than fastest computer
  • Minimal storage requirements.
  • Minimal power requirements
  • They are inexpensive to build, being made of common biological materials.
  • The clear advantage is that we have a distinct memory block that encodes bits.
  • Using one template strand as a memory block also allows us to use its compliment. As another  memory block, thus effectively doubling our capacity to store information.
  • More powerful than the world’s most powerful supercomputer
  • DNA computers smaller than any computer

 DISADVANTAGES

  • Generating solution sets, even for some relatively simple problems, may require impractically large amounts of memory (lots and lots of DNA strands are required)
  • Many empirical uncertainties, including those involving: actual error rates, the generation of optimal encoding techniques, and the ability to perform necessary bio-operations conveniently in vitro (for every correct answer there are millions of incorrect paths generated that are worthless).
  • DNA computers could not (at this point) replace traditional computers.
  • They are not programmable and the average dunce can not sit down at a familiar keyboard and get to work.
  • It requires human assistance.

THE FUTURE OF DNA COMPUTING

The significance of this research is two-fold: it is the first demonstrable use of DNA molecules for representing information, and also the first attempt to deal with an NP-complete problem. But still much more work needs to be done to develop error-resistant and scalable laboratory computations. Designing experiments that are likely to be successful in the laboratory and algorithms that proceed through polynomial-sized volumes of DNA is the need of the hour. It is unlikely that DNA computers will be used for tasks like word processing, but they may ultimately find a niche market for solving large-scale intractable combinatorial problems. The goal of automating, miniaturizing and integrating them into a general-purpose desktop DNA computer may take much longer time.

REFERENCES

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