Friday, May 15, 2009

New Support for the 'RNA World' Hypothesis

From Nature:

"An elegant experiment has quashed a major objection to the theory that life on Earth originated with molecules of RNA.

John Sutherland and his colleagues from the University of Manchester, UK, created a ribonucleotide, a building block of RNA, from simple chemicals under conditions that might have existed on the early Earth."

"Sutherland points out that the sequence of steps he uses is consistent with early-Earth scenarios — those involving methods such as heating molecules in water, evaporating them and irradiating them with ultraviolet light. And breaking RNA's synthesis down into small, laboratory-controlled steps is merely a pragmatic starting point, he says, adding that his team also has results showing that they can string nucleotides together, once they have formed. 'My ultimate goal is to get a living system (RNA) emerging from a one-pot experiment. We can pull this off. We just need to know what the constraints on the conditions are first.'"

However, another website reported that,

"'But while this is a step forward, it’s not the whole picture,' Ferris points out. 'It’s not as simple as putting compounds in a beaker and mixing it up. It’s a series of steps. You still have to stop and purify and then do the next step, and that probably didn’t happen in the ancient world.'"

I'm curious about how this stopping and purifying affects things. I assume purifying means removing chemicals not related to those involved in RNA synthesis. Do these chemicals prohibit any reactions related to RNA synthesis? I have no clue, though I would assume that these researchers are competent enough to either know that they don't or to have proposed a natural mechanism that would remove such chemicals. Maybe these chemicals can also bind to RNA precursors. In that case the odds of RNA production on the early earth would be lower than in the lab, but of course the early earth is vastly larger than any lab setup and has millions of times more time than any experimenter could afford to spare.

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