Origin of Life: Extreme odds (Introduction)

by David Turell , Friday, January 03, 2014, 05:40 (3979 days ago) @ David Turell

&quot;Probabilities of the emergence, by chance, of different versions of the breakthrough system in an O-region: a back-of-the-envelope calculation of the upper bounds&#13;&#10; -...A ribozyme replicase consisting of ~100 nucleotides is conceivable, so, in principle, spontaneous origin of such an entity in a finite universe consisting of a single O-region cannot be ruled out in this toy model (again, the rate of RNA synthesis considered here is a deliberate, gross over-estimate).&#13;&#10; &#13;&#10;The requirements for the emergence of a primitive, coupled replication-translation system, which is considered a candidate for the breakthrough stage in this paper, are much greater. At a minimum, spontaneous formation of the following is required:&#13;&#10; &#13;&#10;- Two rRNAs with a total size of at least 1000 nucleotides&#13;&#10; &#13;&#10;- Approximately 10 primitive adaptors of about 30 nucleotides each, for a total of approximately 300 nucleotides&#13;&#10; &#13;&#10;- At least one RNA encoding a replicase, about 500 nucleotides (low bound)is required. Under the notation used here, n = 1800, resulting in E <10-1018.&#13;&#10; &#13;&#10;In other words, even in this toy model that assumes a deliberately inflated rate of RNA production, the probability that a coupled translation-replication emerges by chance in a single O-region is P < 10-1018. Obviously, this version of the breakthrough stage can be considered only in the context of a universe with an infinite (or, at the very least, extremely vast) number of O-regions.&#13;&#10; &#13;&#10;The model considered here is not supposed to be realistic by any account. It only serves to illustrate the difference in the demands on chance for the origin of different versions of the breakthrough system and, hence, the connections between these versions and different cosmological models of the universe.&quot;-peer-reviewed article, The Cosmological Model of Eternal Inflation and the Transition from Chance to Biological Evolution in the History of Life, Biology Direct 2 (2007): 15, doi:10.1186/1745-6150-2-15