Unit Membrane Model

Lamellar model was supported by Robertson. According to Robertson -

• All biomembrane have similar structure (like PM), on the basis of this observation put forward the concept of Unit membrane.
• According to unit membrane concept - all biomembranes from prokaryotes to eukaryotes have similar trilamellar structure.

• A unit membrane has a thickness of 75Å. (nuclear membrane thicker than 75Å) and made of 2 or more layer.
• Each of 2 electron dense surface layers is 20Å thick, it is formed of extend or b-protein molecules.
• Outer protein layer consists of mucoprotein. Inner protein layer consists of non-mucoprotein.
• Central electron transparent layer is 35Å thick, which is c/o bimolecular layer of phospholipids.
• Drawback of unit membrane model - This model also doesn't explain permeability & elasticity of PM.