DNA
Computers Take Shape
Scientists have made a small but vital
step forward in the quest to harness the vast computing
potential of DNA.
BBC News Online ©
2000 Science Editor Dr David
Whitehouse
Wednesday, 12 January, 2000, 19:00 GMT
The
US team show that DNA computing can be simplified by
attaching the molecules to a surface and then using them to
tackle real and complex problems.
DNA computing is still very much a dream
for scientists. They hope to harness the enormous
data-storing capacity of DNA, biological molecules that are
also able to perform operations similar to a computer's.
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.
Simpler and more accessible
The new research, published in the journal
Nature, reports the development of novel surface chemistry
that greatly simplifies the complex and repetitive steps
previously used in rudimentary DNA computers.
It takes DNA out of the test tube and puts
it on a solid surface, making the technology simpler, more
accessible and more amenable to the development of larger
DNA computers.
"It demonstrates DNA computing on
surfaces, which provides a relatively simple pathway to
upscaling DNA computing to solve large problems," says
team leader Lloyd Smith of the University of
Wisconsin-Madison.
In the experiments, DNA molecules were
applied to a small glass plate overlaid with gold. The DNA
was modified so that all the possible answers to a
computationally difficult problem were included. By exposing
the molecules to certain enzymes, the molecules with the
wrong answers were weeded out, leaving only the DNA
molecules with the right answers.
Mega-memory
The appeal of DNA computing lies in the
fact that DNA molecules can store far more information than
any existing computer memory chip. It has been estimated
that a gram of dried DNA can hold as much information as a
trillion CDs.
What is more, in a biochemical reaction
taking place in a tiny surface area, hundreds of trillions
of DNA molecules can operate in concert, creating a parallel
processing system that resembles the processing architecture
of the most powerful supercomputer.
The logic behind conventional digital
computers represents information as a series of electrical
impulses using ones and zeros. DNA computing depends on
information represented as a pattern of molecules arranged
on a strand of DNA.
Question of scale
Conventional computing, with ever more and
smaller features packed onto the silicon chips that power
it, is approaching the limits of miniaturisation. Many
believe that DNA computing is a way around that barrier.
Current DNA computing technology,
Professor Smith emphasises, is still far from overtaking the
silicon chip. He says his new method is simply a testbed for
working out an improved and simpler chemistry for DNA
computing.
Nevertheless, he adds, the new surface
chemistry provides an opportunity for harnessing DNA to make
the biggest non-conventional computer yet: "We're
interested in scale up. We believe that based on the
principles we've worked out here, we can see scaling up
within a few years by a factor of a trillion or more."
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