Model Suggests How Life's Code Emerged From Primordial Soup
Added: Sun, 30 Aug 2009 23:00:00 UTC
Thanks to rod-the-farmer for the link.
ScienceDaily (Aug. 31, 2009) — In 1952, Stanley Miller filled two flasks with chemicals assumed to be present on the primitive Earth, connected the flasks with rubber tubes and introduced some electrical sparks as a stand-in for lightning. The now famous experiment showed what amino acids, the building blocks of proteins, could easily be generated from this primordial stew. But despite that seminal experiment, neither he nor others were able to take the next step: that of showing how lifeâs code could come from such humble beginnings.
By working with the simplest amino acids and elementary RNAs, physicists led by Rockefeller Universityâs Albert J. Libchaber, head of the Laboratory of Experimental Condensed Matter Physics, have now generated the first theoretical model that shows how a coded genetic system can emerge from an ancestral broth of simple molecules. âAll these molecules have different properties and these properties define their interactions,â says first author Jean Lehmann, a postdoctoral fellow in the lab, whose work appears in the June issue of PLoS One. âWhat are the constraints that allow these molecules to self-organize into a code? We can play with that.â
The genetic code is a triplet code such that every triplet sequence of letters on messenger RNA corresponds to one of the 20 amino acids that make up proteins. Molecular adapters called transfer RNAs (tRNAs) then convert this information into proteins that can achieve some specific tasks in the organism. Letâs say that each triplet sequence on messenger RNA, known as a codon, represents an outlet that can only accept a tRNA with a complementary anticodon. Translation works because each codon-anticodon match corresponds with an amino acid. As each tRNA is plugged in, a chain of amino acids is formed in the same order as the codons until translation is complete.
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