Page 124 - Introduction to Colloid and Surface Chemistry

114 Liquid-gas and liquid-liquid interfaces

of the cell membrane to specific metabolites, however, requires
modification of the simple lipid bimolecular layer model, and the
basic structure is thought to consist of the lipid bimolecular layer with
62
protein both adsorbed on to and incorporated into it , as illustrated
in Figure 4.28.

Figure 4.28 Schematic representation of a biological cell membrane. A bimolecular
layer of phospholipid with hydrocarbon chains orientated to the interior and
hydrophtlic groups on the outside is penetrated by protein (shaded areas). Protein is
also found adsorbed at the membrane surface

Artificially prepared monolayers have been used successfully as
models for studying certain biological processes. Schulman and
Rideal 162 investigated the action of agglutinating (coagulating) and
lytic agents on red blood cells by the monolayer technique. A mixed
film of 20 per cent cholesterol and 80 per cent gliadin was used to
represent the red blood cell membrane. If was found that lytic agents
penetrate into this monolayer, whereas agglutinating agents only
adsorb on to the underside of the film. This implies that red blood
cells are altered structurally (lysis) owing to the penetration of lytic
agents into the membrane, while agglutinating agents merely adsorb
on to the membrane surface.