For Lane, these reactions in all probability happened around the piping hot black smokers of the oceanic abyss, where the Earth's crust is wrenched apart by immense geological forces. "In environments like hydrothermal vents it is likely, but as yet experimentally unproven, that a range of amino acids and nucleotides would be formed by the laws of chemistry," he says. Local currents, he adds, would probably draw the molecules together, making it more likely that self-replicating chains of RNA could form and associate with amino acids.
In other words, the genetic code is the inevitable consequence of affinities between the molecular building blocks of RNA and those of the proteins they code for. If he's right, it will explain why individual triplets always code for the same amino acids, whether in a virus or a human.
Yarus works with artificial RNA and has shown that these chemical affinities do exist. Mix strands of RNA with amino acids and the amino acids will more or less spontaneously nestle up to their corresponding triplets. "Yarus found that anticodons [a type of triplet found in some RNAs] were particularly good in this regard and bind the 'correct' amino acid with up to a millionfold greater affinity than other amino acids," says Nick Lane of University College London.
On the experimental side, some researchers, such as George Cody at the Carnegie Institution of Washington, D.C., are trying to work out the basic rules of organic chemistry for exotic environments that might have been relevant to the origin of life. Cody, for example, has worked on unraveling organic interactions at the kinds of temperatures and pressures that obtain at deep ocean vents. Mike Russell at the Jet Propulsion Laboratory in Pasadena, California, (author of “First Life,” January–February 2006) is building a large chamber to model the geochemistry of those environments. Shelley Copley at the University of Colorado at Boulder has been sorting out the intermediate chemistry leading to the current nucleic acid–protein system of genetic coding, with an eye toward resolving the chicken-and-egg problem.
Sure enough, when the pair looked at where amino acids sat in the ribosome, they found that 11 of 20 standard amino acids were far more likely than not to be positioned next to the "right" triplet according to the genetic code
ShitMyDadSays "Science and Mother Nature are in a marriage where Science is always surprised to come home and find Mother Nature blowing the neighbor."
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