Origin of eukaryota from Cyanobacterium: membrane evolution theory

It has been currently estimated that the life generated about four billion years ago in the primitive sea as a result of the chemical evolution. There is no doubt that, at that time, the protoorganism was a prokaryotic monad, formed from a certain aggregate of primitive proteins, nucleic acids, and other macromolecules and wrapped with (phospho)lipid membrane. Some workers have proposed that the macromolecules involved in the formation of the life were adsorbed on surface of clay particles in the primeval soup (Cairns-Smith 1982). However, it seems very unlikely that such a simple aggregation of the macromolecules would lead to the formation of a vital cell. The reasons for such uncertainty which have been discussed (see Nakamura 1987c) are: (1) The extant cells, without exception, are wrapped by a single membrane consisting of phospholipid bilayer. (2) Life is expressed only in a closed, rather than open, system isolated from the environment by the plasma membrane.