Describe the Fluid Mosaic Model of Membranes, composition, asymmetry?

Proposed in 1972 by Singer and Nicholson (UCSD) • Lipids form a viscous, two-dimensional solvent into which proteins are inserted and integrated more or less deeply • Integral proteins are firmly associated with the membrane, often spanning the bilayer • Peripheral proteins are weakly associated and can be removed easily – Some are noncovalently attached – Some are linked to membrane lipids Integral proteins float in this sea of lipid. • Two leaflets have different lipid compositions • Outer leaflet is often more positively charged