Aparecimento da vida

Cientistas Britânicos poderão ter dado um passo importante na compreensão do aparecimento da vida na Terra e de como a partir de moléculas químicas se terá chegado à molécula do RNA:

“An English chemist has found the hidden gateway to the RNA world, the chemical milieu from which the first forms of life are thought to have emerged on earth some 3.8 billion years ago.
He has solved a problem that for 20 years has thwarted researchers trying to understand the origin of life — how the building blocks of RNA, called nucleotides, could have spontaneously assembled themselves in the conditions of the primitive earth. The discovery, if correct, should set researchers on the right track to solving many other mysteries about the origin of life. It will also mean that for the first time a plausible explanation exists for how an information-carrying biological molecule could have emerged through natural processes from chemicals on the primitive earth…”
Mas há quem não esteja de acordo: “Dr. Sutherland’s proposal has not convinced everyone. Dr. Robert Shapiro, a chemist at New York University, said the recipe “definitely does not meet my criteria for a plausible pathway to the RNA world.” He said that cyano-acetylene, one of Dr. Sutherland’s assumed starting materials, is quickly destroyed by other chemicals and its appearance in pure form on the early earth “could be considered a fantasy”.”
“Dr. Sutherland replied that the chemical is consumed fastest in the reaction he proposes, and that since it has been detected on Titan there is no reason it should not have been present on the early earth.
If Dr. Sutherland’s proposal is correct it will set conditions that should help solve the many other problems in reconstructing the origin of life. Darwin, in a famous letter of 1871 to the botanist Joseph Hooker, surmised that life began “in some warm little pond, with all sorts of ammonia and phosphoric salts.” But the warm little pond has given way in recent years to the belief that life began in some exotic environment like the fissures of a volcano or in the deep sea vents that line the ocean floor.
Dr. Sutherland’s report supports Darwin. His proposed chemical reaction take place at moderate temperatures, though one goes best at 60 degrees Celsius. “It’s consistent with a warm pond evaporating as the sun comes out,” he said. His scenario would rule out deep sea vents as the place where life originated because it requires ultraviolet light”

Leiam mais, aqui e aqui. Leiam em português, aqui e aqui.

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