Membrane Structure and Properties

Abstract

Listen

Translate article

The major constituents of cell membranes are lipids and proteins. Lipid molecules consist of a polar headgroup to which is attached one or two long hydrocarbon chains or tails. In Figure 2.1 is the chemical structure of one such lipid, phosphatidylcholine, and below this a schematic diagram of the molecule which illustrates its important properties. The hydrocarbon tails of the molecule are hydrophobic — they tend to avoid coming into contact with water molecules. The polar headgroup on the other hand is hydrophilic and prefers an aqueous environment. If lipids are mixed with water then a number of structures are formed with the common feature that the hydrocarbon tails congregate together to protect themselves from contact with the aqueous medium. In Figure 2.1 two of these are illustrated — a spherical micelle and a monolayer on the water surface.