ABSTRACT

The membrane was fluid because of the fluid nature of lipid layer and mosaic due to the assortment of protein molecules dispersed within it. Evidence for the old model that once seemed compelling, seemed not only weak and unpersuasive, but almost vaporous. Even the idea that the membrane of red blood cells fractured during hemolysis seemed wrong. The presence of proteins in membranes, in which he believed, and their passage across them were very different matters. It was one thing for a protein to enter a membrane, but totally different to cross it. Despite the radical change he had brought about, his ideas about the physiological character and functional properties of biological membranes had remained unchanged. Most significantly, there was evidence of large membrane pores. Proteins were by in large rigid, roughly spherical polar or water-soluble molecules, while biological membranes were mainly comprised of water-avoiding or nonpolar lipids.