Lipid bilayer

A lipid double layer (or bilayer ) is a structure constituting the many amphiphilic lipids in the mixture with a polar solvent (e.g., water). In the mixture with an apolar solvent (e.g., oil) to an inverse double lipid layer forms.

A lipid double layer composed of amphiphilic lipids (mostly hydrocarbon chains ) have a hydrophilic and hydrophobic moiety. In the polar solvent is a double layer, wherein the hydrophobic portion to the inside and the hydrophilic portion facing outwards is formed. In nonpolar solvents, the situation reverses according to ( so-called inverse double lipid layer).

A lipid bilayer is virtually impermeable to polar molecules or macromolecules, but at the same time very flexible and mechanically difficult to destroy. For this reason, even leaving a puncture with a pipette no hole in the membrane. Similarly, water and small uncharged molecules diffuse through the lipid bilayer without damaging them. By lipid solvents, and lipases lipid bilayer can be destroyed.

Lipid bilayer may be present in different phases which differ in the level of the layer especially in the mobility of the lipids. In the gel-like or liquid-crystalline phase, the lipid tails are densely arranged with each other while they are disordered and highly mobile in the liquid or fluid phase as in a liquid. At this stage the double lipid layer is also described as two-dimensional liquid.

1925 described Gorter Grendel first and a lipid bilayer as a major constituent of biological membranes (such as the cell membrane ). It serves as the interface between cell compartments and the interior and exterior of the cell. The lipid bilayer of a biological membrane consists essentially of phospholipids, which are usually in the liquid phase, so that the other components of the membrane remain movable.