‘Fluid Mosaic Model' was proposed by Singer and Nicholson as the generalized model for structure of all cell membranes. According to the fluid mosaic model, the cell membrane consists of a highly viscous fluid matrix of two layers of phospholipid molecules. Protein molecules occur not in a continuous layer but as separate particles asymmetrically arranged in a mosaic pattern. Some of these (peripheral/extrinsic proteins) are loosely bound at the polar surfaces of lipid layers while others (integral/intrinsic proteins) penetrate deeply into the lipid layer.
