i.
Kalau kesimpulan John Sutherland dkk. ini confirmed
maka betul-betul tammat sebagai kitab suci..
Found: the origin of life
Scientists solve the mystery of how the Earth was transformed
By Steve Connor, Science Editor
Thursday, 14 May 2009
AFP
Scientists
have developed an experiment demonstrating how the
very first self-replicating molecules may have formed about 4 billion
years ago when the Earth was like any other lifeless planet. Today
earth has an estimated 50 million species
*
Of all the scientific mysteries, this is probably the greatest one of all –
how did life on Earth begin? We are not talking about how it evolved into the
diversity of lifeforms we see today. We are talking about how it originated in
the first place.
For all his immense insight into evolution, Charles
Darwin himself was stumped. He suggested that whatever the mechanism
was that had led to the first replicating lifeforms, it most probably
arose in some "warm little pond", a primordial soup of pre-biotic
ingredients where the seed of life first germinated on the early Earth.
Now
scientists have developed an experiment demonstrating how the very
first self-replicating molecules may have formed about 4 billion years
ago when the Earth was like any other lifeless planet that had yet to
experience the radical transformation of living, breathing creatures.
Related articles
* More Science News
John Sutherland and colleagues at Manchester University have broken
new ground by being able to synthesise almost from scratch two of the
four building blocks of RNA, the self-replicating molecule that many
scientist believe to be the most likely contender for the original
molecule of life. Dr Sutherland believes that he has shown how it was
possible to make all the building blocks of RNA from the simple
chemicals that would have existed on Earth 4 billion years ago.
"We've
made the building blocks of RNA from what was around on the early Earth
and is still around in interstellar space and in the atmosphere of
Saturn's moon Titan," Dr Sutherland said.
"We haven't yet made
the RNA molecule itself but we've made two of the four sub-units or
building blocks. It suggests that making the molecule is possible. The
building blocks are strung together and doing that is actually easier
than making the building blocks themselves," he said.
RNA is the
less familiar cousin of DNA, the genetic blueprint of life. Like DNA,
the RNA molecule can carry and transmit information from one generation
to the next. But unlike DNA, RNA is a relatively simple molecule that
many scientists believed could have been quite easy to synthesise in
the harsh environment of the early Earth. The trouble with this idea –
which is more than 40 years old – is that no one has been able to join
up the three components, the sugars, bases and phosphates that make up
each of the four building blocks of RNA, under the sort of conditions
that existed 4 billion years ago. Dr Sutherland, however, has shown in
a study published in the journal Nature that this is indeed possible.
"The
trouble is, the human eye sees the three components of RNA and so the
human brain assumes that to make the molecule you should combine those
three components. People have found that they can make the sugars and
the bases but the key thing they can't do is to join them together," Dr
Sutherland said.
"And so for 40 or so years they have worked on
the problem and have become so frustrated that they have decided that
RNA, although very desirable, is just too complicated and so there must
have been a simpler molecule that spawned RNA. We've just changed the
order of assembly of the pieces, but it's overcome the dogma that it
cannot be done," he said.
In trying to explain how life began on
Earth, scientists have attempted to formulate theories to account for
how the first self-replicating molecule came into existence. One of the
earliest theories was the "primordial soup", where simple molecules
mixed together in a broth that was regularly energised by ultraviolet
light and electric storms.
Over time, these simple molecules
would have combined to form more complex substances containing the
all-important atomic ingredients of life – oxygen, carbon, hydrogen and
nitrogen. Although scientists were able to make the building blocks of
proteins in this way, they failed to do the same with DNA or RNA.
Scientists
first proposed that RNA preceded proteins in the 1960s, but it was not
until the 1980s that they received strong support for the idea. Thomas
Cech at the University of Colorado and Sidney Altman at Yale, found
that RNA could act as a catalyst by speeding up a chemical reaction and
yet being unchanged in the process – a feat normally reserved for
enzymes.
This was the first hard evidence that RNA, a molecule
that can replicate and store genetic information, could also have
triggered the first synthesis of life's proteins. Most scientists now
believe that there was an "RNA world" early in the Earth's history from
which all present-day life is ultimately descended.
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Jusfiq Hadjar gelar Sutan Maradjo Lelo
Allah yang disembah orang Islam tipikal dan yang digambarkan oleh al-Mushaf itu
dungu, buas, kejam, keji, ganas, zalim lagi biadab hanyalah Allah fiktif.
