An Electron Diffraction Study of the Structure and Orientation of the Lipids in Yeast and Bacterial Cell Walls

While it is generally agreed that many of the permeability relationships of different types of living cells depend on the chemical and physical properties of the lipids or lipo-proteins in the surface layers, no direct evidence of the nature of the molecular organization of these fatty components as they occur in situ has yet been produced. Such suggestions as have been made have been based mainly on permeability studies of cells and model membranes, while examinations of the properties and behaviour of the isolated components by the sensitive monolayer technique (Schulman & Rideal, 1937) has proved a useful guide to the possible molecular structure of the cell membrane. Supporting evidence has been derived from polarization and electron microscopy, and from impedance and electrophoresis measurements. The thinness of the cell membrane has so far prevented direct study by X-ray diffraction, although this method of analysis has successfully been applied to the study of isolated fatty components (Schmitt & Palmer, 1940).