Re: Article: Mountains of new data are challenging old views
- From: "Anon." <bob.ohara@xxxxxxxxxxx>
- Date: Tue, 11 Sep 2007 15:20:03 -0400 (EDT)
Robert Karl Stonjek wrote:
Genome 2.0
Mountains of new data are challenging old views
Patrick Barry
When scientists unveiled a draft of the human genome in early 2001, many
cautioned that sequencing the genome was only the beginning. The long list
of the four chemical components that make up all the strands of human DNA
would not be a finished book of life, but a road map of an undiscovered
country that would take decades to explore.
Only 6 years later, the landscape of the genome is already proving to be
dramatically different than most scientists had expected.
The established view of the genome began to take shape in 1958, just 5 years
after Francis Crick and James D. Watson worked out the structure of DNA. In
that year, Crick expounded what he called the "central dogma" of molecular
biology: DNA's genetic information flows strictly one way, from a gene
through a series of steps that ends in the creation of a protein. That
principle developed into a modern orthodoxy, according to which a genome is
a collection of discrete genes located at specific spots along a strand of
DNA. This old view got the basics right: that genes encode proteins and that
proteins do the myriad work necessary to keep an organism alive.
Researchers slowly realized, however, that genes occupy only about 1.5
percent of the genome. The other 98.5 percent, dubbed "junk DNA," was
regarded as useless scraps left over from billions of years of random
genetic mutations. As geneticists' knowledge progressed, this basic picture
remained largely unquestioned. "At one time, people said, 'Why even bother
to sequence the whole genome? Why not just sequence the [protein-coding
part]?'" says Anindya Dutta, a geneticist at the University of Virginia in
Charlottesville.
Closer examination of the full human genome is now causing scientists to
return to some questions they thought they had settled. For one, they're
revisiting the very notion of what a gene is. Rather than being distinct
segments of code amid otherwise empty stretches of DNA-like houses along a
barren country road-single genes are proving to be fragmented, intertwined
with other genes, and scattered across the whole genome.
Even more surprisingly, the junk DNA may not be junk after all.
Well, perhaps surprising to anyone who had slept through the preceding
two decades.
Most of this
supposedly useless DNA now appears to produce transcriptions of its genetic'Alu, 'Alu? Anybody there?
code, boosting the raw information output of the genome to about 62 times
what genes alone would produce. If these active nongene regions don't carry
code for making proteins, just what does their activity accomplish?
Which is a subtle way of saying that we've known for several years what
a lot of junk DNA is.
The annoying thing is that there shouldn't be any need to mis-represent
the state of knowledge we had 10 years ago - the advances being made now
are still wonderous.
Bob
--
Bob O'Hara
Department of Mathematics and Statistics
P.O. Box 68 (Gustaf Hällströmin katu 2b)
FIN-00014 University of Helsinki
Finland
Telephone: +358-9-191 51479
Mobile: +358 50 599 0540
Fax: +358-9-191 51400
WWW: http://www.RNI.Helsinki.FI/~boh/
Blog: http://deepthoughtsandsilliness.blogspot.com/
Journal of Negative Results - EEB: www.jnr-eeb.org
.
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- From: Robert Karl Stonjek
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