A<unk>  or<unk>  lipid membrane (BLM) is a membrane or zone of a membrane composed of lipid molecules (usually phospholipids).  The<unk>  is a critical component of all biological membranes, including cell membranes, and so is absolutely essential for all life on Earth.  Its essential structure was discovered in 1925 by two Dutch physicians, E.Gorter and F.Grendel, while they were comparing the surface area of human erythrocytes  with that of the isolated lipids in a Langmuir Blodgett trough.  They found that the area of lipids from a known number of erythrocytes, when spread out on the trough, was just twice the calculated surface area of the erythrocytes. They concluded, correctly, that the membrane is two lipid molecules thick and proposed it is made of a<unk> .
Lipid bilayer
Membrane skeleton
Electron shell
Viral envelope
Viral tegument
Phospholipid
Liposome
Capsid