fluid mosaic model

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fluid mosaic model A widely accepted model, proposed by S. J. Singer and G. L. Nicholson in the 1970s, for the structure of cell membranes. It is based on a lipid bilayer forming the framework of the membrane, with proteins randomly embedded in it; these proteins may be restricted to either lipid layer (extrinsic proteins) or they may span both (intrinsic proteins), producing an asymmetric structure (see illustration). This structure allows the lateral movement of the constituent phospholipid and protein molecules of the membrane.