From: Spudboy100@aol.com
Date: Wed Feb 26 2003 - 11:18:27 MST
<A HREF="http://www.sciam.com/html/invite_newschannel.html">http://www.sciam.com/html/invite_newschannel.html>
February 25, 2003
The Guinness Book of World Records has crowned it the world's smallest
Both models of the molecular computer are so-called automatons. Given an
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: Wed Feb 26 2003 - 11:20:57 MST
New DNA Computer Functions sans Fuel
In 2001, scientists at the Weizmann Institute of Science in Israel announced
that they had manufactured a computer so small that a single drop of water
would hold a trillion of the machines. The devices used DNA and enzymes as
their software and hardware and could collectively perform a billion
transitions each second. Now the same team, led by Ehud Shapiro, has
announced a novel model of its biomolecular machine that no longer requires
an external energy source and performs 50 times faster than its predecessor
did.
biological computing device. Many designs for minuscule computers aimed at
harnessing the massive storage capacity of DNA have been proposed over the
years. Earlier schemes have relied on a molecule known as ATP, which is a
common source of energy for cellular reactions, as a fuel source. But in the
new set up, a DNA molecule provides both the initial data and sufficient
energy to complete the computation. Shapiro and his colleagues describe their
DNA computer in a report published online this week by the Proceedings of the
National Academy of Sciences.
input string comprised of two different states, an automaton uses
predetermined rules to arrive at an output value that answers a particular
question. For example, it can determine whether a string containing only a's
and b's has an even number of a's, or if all the b's are preceded by a's. In
the latest design, two DNA molecules bond together to perform the
computational steps. An enzyme known as FokI acts as the computer's hardware
by cleaving a piece of the input molecule and releasing the energy stored in
the bonds. This heat energy then powers the next computation.