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Old 08-09-2014, 11:14 AM   #55
Dave Lane Dave Lane is offline
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Here's a very very short and non-scientific friendly bit on abiogenesis.

It is now widely agreed that at the origin of life there was not the current DNA/(RNA)/protein system for gene information on one hand and catalysis, regulation, and structural function on the other. It would beg the question, what came first, protein or DNA? Protein catalysis without gene information, which allows it to be maintained and propagated, is not sufficient in the long term, and DNA gene information without catalysis, necessary for the function of life, would be useless as well.

Instead, it is assumed that RNA acted as a precursor of both protein and DNA, in the sense that it can serve both as catalyst (like protein enzymes) and as carrier of genetic information. Even in the modern cell ribozymes (catalytic RNAs) still play a vital, albeit limited, role. In the ribosome, the synthesis of the peptide chains of proteins from RNA code is accomplished by ribozymes. They also catalyze splicing of RNA.

The hypothesis that a so-called RNA World was involved in the early evolutionary stages of life is now an almost universally held view (Joyce 2002, Orgel 2004, The RNA World 2006). Could this RNA World have stood at the ultimate origin of life? This is currently still an open question. The RNA system may be too complex to have arisen without synthesis by a genetic precursor or prior enzyme-less metabolism (options discussed below). Yet while there are still substantial problems, there are now good leads for simple, spontaneous processes on the early Earth for both the synthesis of nucleotides and their concatenation to oligonucleotides.
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