>>2094For over a century, people have suggested that cells are enclosed in an oily membrane, because there are higher or lower concentrations of many water-soluble substances inside cells, than in the blood, lymph, and other extracellular fluids, and the idea of a membrane was invoked (W. Pfeffer, 1877; E. Overton, 1895, 1902) to explain how that difference can persist. (By 1904, the idea of a membrane largely made of lecithin was made ludicrous by A. Nathansohn's observation that water-soaked lecithin loses its oily property, and becomes very hydrophilic; the membrane was supposed to exclude water-soluble molecules while admitting oil-soluble molecules.)
Inside the cell membrane, the cell substance was seen as a watery solution. Biochemistry, as a profession, was strongly based on the assumption that, when a tissue is ground up in water, the dilute extract closely reflects the conditions that existed in the living cell. Around 1970, when I tried to talk to biochemists about ways to study the chemistry of cells that would more closely reflected the living state, a typical response was that the idea was ridiculous, because it questioned the existence of biochemistry itself as a meaningful science.. But since then, there has been a progressive recognition that organization is more important in the life of a cell than had been recognized by traditional biochemistry. Still, many biochemists thoughtlessly identify the chemistry of the living cell with their study of the water-soluble enzymes, and relegate the insoluble residue of the cell to "membrane-associated proteins" or, less traditionally, to "structural proteins." It has been several decades since the structural/contractile protein of muscle was found to be an enzyme, an ATPase, but the idea that the cell itself is a sort of watery solution, in which the water-soluble enzymes float, randomly mingling with dissolved salts, sugars, etc., persists, and makes the idea of a semipermeable membrane seem necessary, to separate a "watery internal phase" from the watery external phase. Physical chemists have no trouble with the fact that a moist protein can absorb oil as well as water, and the concept that even water-soluble enzymes have oil-loving interiors is well established. If that physical-chemical information had existed in Overton's time, there would have been no urge to postulate an oily membrane around cells, to allow substances to pass into them, in proportion to their solubility in oil.
Because biochemists like to study their enzymes in watery test-tube solutions, they find it easy to think of the cell-substance as a watery solution. With that belief, it is natural that they prefer to think of the primeval ocean as where life originated. Their definitions of chemical reactions and equilibria in the water-phase (and by extension in cells) ignore the alternative reactions and equilibria that would occur in an environment in which ordinary water was not the dominant medium. By this failure to consider the alternatives, they have created some problems that are hard to explain. For example, the polymerization of amino acids into protein is energetically expensive in water, but it is spontaneous in a relatively dry environment, and this spontaneous reaction creates non-random structures with the capacity for building larger structures, with stainable bilayer "membranes," and with catalytic action. (Sidney Fox, 1965, 1973.) Similarly, the problem of ATP synthesis essentially disappears when it is considered in an environment that controls water. The scientific basis for the origin of life in a "primeval soup" never really existed, and more people are now expressing their scepticism. However, biochemists have their commitments: