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MILES O'BRIEN:  It's one of the most profound questions of all.
How did life on Earth begin?
NICHOLAS HUD:  Early on, when I got into science, I decided that
I'd like to work on a big question, a question that would
be interesting all of my life. And, the more I thought
about origin of life, the more I thought this really
fits the bill.
MILES O'BRIEN:  With support from the National Science
Foundation, Georgia Tech biochemist Nicholas Hud and a
team at the Center for Chemical Evolution are working to chip
away at the question.  They are homing in on how chain-like
chemicals called polymers first came together and evolved 3 and
a half to 4 billion years ago.
NICHOLAS HUD:  And, we're thinking that on the early Earth,
the molecules that gave rise to the first polymers of life--
RNA, DNA--would have actually started by small molecules
interacting with each other and forming very ordered structures.
MILES O'BRIEN:  In other words, they assembled themselves.
NICHOLAS HUD:  If you look at this model, what you see in the
center are what we call the based pairs.
MILES O'BRIEN:  Hud's focus is the RNA molecule -- a chemical
sibling to the better known DNA. RNA does the genetic heavy
lifting in a cell -- translating the information stored in DNA
into the materials that are needed to build a living
organism. Some researchers believe that RNA, or an RNA-like
polymer, was the first molecule of life.  Hud's team works with
chemicals that are believed to have been present on
the early Earth.
BRIAN CAFFERTY:  So, we can then look at this chemical inventory
and we can select from it, the molecules that might have been
important for getting something like life kick-started.
MILES O'BRIEN:  So far, none of the labs working on chemical
evolution has been able to coax actual RNA to self-assemble in
the lab. But Hud and his team have identified a couple of
molecules that make a structure that almost looks like RNA.
NICHOLAS HUD:  They start out by simply pairing together.  Then,
they stack together.  They form structures that go from perhaps
two to six molecules, to 12 molecules until we get up to the
level of thousands--even hundreds of thousands of
molecules associated together.
MILES O'BRIEN:  Hud says these may well be some of the chemical
ancestors of RNA as we know it today.
NICHOLAS HUD:  If we take the components that we have in RNA
today and we change them, sometimes just by one or two
atoms, what we find is that they react together much more easily
and they seemingly put us on the road towards making what we
might call a proto-RNA polymer.
MILES O'BRIEN:  Putting chemistry to work sleuthing out
the origins of life--a bit like genealogy perhaps, but
going way, way back on the family tree.
For Science Nation, I'm Miles O'Brien.
