ON THE EMERGENCE OF LIFE VIA CATALYTIC IRON-SULFIDE MEMBRANES

We propose that the precipitation of a gelatinous iron-sulphide membra ne is the necessary first step towards life. Membrane vesicles were in flated with alkaline, sulphide-bearing hydrothermal (<200-degrees-C) s olution and grew on a submarine sulphide mound in acid iron-bearing Ha dean seawater. Once a critical size had been reached (0.1-1 mm) vesicl es would have budded contiguous self-similar daughters. We assume that the membrane was rendered insulating by the adsorption and/or oxidati ve precipitation of organic and organosulphur compounds. As a conseque nce of the naturally induced proton-motive (chemiosmotic) force, and t he activity of the iron monosulphide redox catalysts within the membra ne, organic compounds would have accumulated within the vesicle. Osmot ically driven growth therefore became more significant with time. The geochemical environment envisaged as responsible for this first step t owards life is consistent with that widely accepted for the early Eart h.