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Molecule of life emerges
Topic Started: May 15 2009, 06:25 PM (265 Views)
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Interesting development supporting the hypothesis life can emerge from non-life.

No, breeze, this is not the Medieval Christian belief in spontaneous generation where rats were found in grain barrels.

Molecule of life emerges from laboratory slime
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CREATING life in the primordial soup may have been easier than we thought. Two essential elements of RNA have finally been made from scratch, under conditions similar to those that likely prevailed during the dawn of life.

The question of how a molecule capable of storing genetic information - even DNA's simpler cousin RNA - could ever have arisen spontaneously in the primordial cooking pot has perplexed scientists for decades. RNA consists of a long chain composed of four different types of ribonucleotides, which each consist of a nitrogenous base, a sugar and a phosphate.

Most people assumed that these three components first formed separately, and then combined to make the ribonucleotides. The only trouble was that it seemed impossible that two of the four bases with particularly unwieldy chemistry ever reacted spontaneously with the sugar.

To tackle this problem, John Sutherland from the University of Manchester, UK, tried to work out a new recipe for RNA that gets by without forcing isolated bases and sugar molecules to react. His team experimented by cooking up ribonucleotides from five small molecules thought to be present in the primordial soup. "We started with the same building blocks as others, but take a different route," Sutherland says.

And this time the cooks seem to have got it right. The recipe and conditions that they came up with to mix the five ingredients - including a good blast of UV light - produce ribonucleotides via a joint precursor molecule that contains both the base and the sugar instead of making each in their free form (Nature, DOI: 10.1038/nature08013).

This package deal sidesteps the problem of getting two unwilling partners to react, but only thanks to another trick, say the researchers. The reaction worked only when phosphate was present right from the start, although it does not react with the mixture until near the final stages. It turns out it is needed as a catalyst and as a chemical buffer early on.

"We don't use any way-out scenarios - all the conditions are consistent with what we know about early Earth," says Sutherland. William Scott, from the University of California in Santa Cruz agrees: "It's a great leap forward that demonstrates how prebiotic RNA molecules may have assembled spontaneously from simple and presumably relatively abundant constituents."
It's a great leap forward that demonstrates how prebiotic RNA molecules may have assembled

The need for UV light suggests life didn't begin in a submarine vent, one possible scenario. Instead, it points towards a warm pond - an idea first mooted by Charles Darwin, who knew nothing of RNA.


Second source: Life’s First Spark Re-Created in the Laboratory.
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ngc1514
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An interesting piece in the May 11th issue of The New Yorker about neurologist Dr. Vilayanur Ramachandran, director of UCSD's Center for Brain and Cognition. The doctor has opened up many interesting lines of research into neurological problems including the "mirror cure" for phantom limb pain and an approach to treating apotemnophilia - the compulsion to have a healthy limb amputated. As the article states, Ramachandran "has a reputation among his peers for being able to solve some of the most mystifying riddles of neuroscience."

Interesting reading, but what caught my attention is his hypothesis on the creation of consciousness in the human brain. He is basing this, in part, on what are known as "mirror neurons," neurons which - from the Wiki article on the subject:
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A mirror neuron is a neuron which fires both when an animal acts and when the animal observes the same action performed by another animal (especially by another animal of the same species).[1] Thus, the neuron "mirrors" the behavior of another animal, as though the observer were itself acting. These neurons have been directly observed in primates, and are believed to exist in humans and other species including birds. In humans, brain activity consistent with mirror neurons has been found in the premotor cortex and the inferior parietal cortex.

The New Yorker article continues:
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One of the theories we put forward," he (Ramachandran) said ... "is that the mirror-neuron system is used for modelling someone else's behavior, putting yourself in another person's shoes, looking at the world from another's point of view. This is called an allocentric view of the world as opposed to the egocentric view. So I made the suggestion that at some point in evolution this system turned back and allowed you to create an allocentric view of yourself. This is, I claim, the dawn of self-awareness."


Amazing! Not fully accepted, of course and the Wiki article does mention a couple citations of cases where
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Two recent studies cast doubt on the importance of mirror neurons in the human brain [26] [27]. These fMRI studies suggest that the signal changes seen in 'mirror neuron regions' of the human brain are not necessarily due to the firing of mirror neurons themselves, but may reflect other processes.
But it is just another instance where it appears mind is just something that the brain does and is not some spark instilled in us from without.

The problem of consciousness and self-awareness remains one of the biggies in the bio-sciences and it's amazing that the first steps in cracking it have, apparently, been taken.
Edited by ngc1514, May 15 2009, 08:44 PM.
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Yes, I've read before about these mirror neurons, and how it's hypothesized these form the basis of self-reflection, self-awarenees.

The beginnings of this can be traced back to Adam Smith's The Theory of Moral Sentiments.
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