Authors: Raul A. Félix de Sousa
A model for biopoesis is proposed where a complex, dynamic ecosphere, characterised by steep redox potentials, precedes and conditions the gradual formation of organismal life. A flow of electrons across the Archean hydrosphere, proceeding from the reducing constituents of the lithosphere and pumped by the photolytic production of oxygen in the Earth's atmosphere is the central feature of this protobiological environment. The available range of electrochemical potentials allows for the geochemical cycling of biogenic elements. In the case of carbon, carboxylation and decarboxylation reactions are essential steps, as in today's organisms. Geochemical evidence for high levels of carbon dioxide in the Earth's early atmosphere and the biological relevance of carboxylations are the basis for a hypercarbonic conception of the primitive metabolic pathways. Conversion of prochiral chemical species into chiral molecules, inherent to hypercarbonic transformations, suggests a mechanistic method for the generation of homochirality through propagation. The solubility of oxygen in lipid materials points to an aerobic course for the evolution of cellularity.
Comments: 39 pages. KEYWORDS: origin of life, geochemical cycles, biogenic elements, oxygen, palaeoatmosphere, homochirality
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