The plasma membrane is an integral constituent of both prokaryotic and eukaryotic cells, enclosing the cytoplasm and other cell components. In the latter, the biological membrane is the primary instrument governing the passage of solutes to the cell interior. A phospholipid bilayer forms the basic structural unit establishing a hydrophobic barrier in the membrane core, thus whilst hydrophobic molecules may be admitted passage, additional biological assemblies are required for the transmission of many molecules. Membrane proteins, as these assemblies are known, also play a role in cell signalling, invoking internal processes on recognition of external stimuli. A schematic of membrane...