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Fluid mosaic model of a cell membrane. The fluid mosaic model explains various characteristics regarding the structure of functional cell membranes.According to this biological model, there is a lipid bilayer (two molecules thick layer consisting primarily of amphipathic phospholipids) in which protein molecules are embedded.
In 1972, S. Jonathan Singer and Garth Nicolson developed new ideas for membrane structure. Their proposal was the fluid mosaic model, which is one of the dominant models now. It has two key features—a mosaic of proteins embedded in the membrane, and the membrane being a fluid bi-layer of lipids.
The phospholipid bilayer structure (fluid mosaic model) with specific membrane proteins accounts for the selective permeability of the membrane and passive and active transport mechanisms. In addition, membranes in prokaryotes and in the mitochondria and chloroplasts of eukaryotes facilitate the synthesis of ATP through chemiosmosis.
This was not the first proposal of a heterogeneous membrane structure. Indeed, as early as 1904 Nathansohn proposed a “mosaic” of water permeable and impermeable regions. [20] But the fluid mosaic model was the first to correctly incorporate fluidity, membrane channels and multiple modes of protein/bilayer coupling into one theory.
Garth L. Nicolson (born October 1, 1943) [1] is an American biochemist who made a landmark scientific model for cell membrane, known as the fluid mosaic model.He is the founder of The Institute for Molecular Medicine at California, and he serves as the president, chief scientific officer and emeritus professor of molecular pathology.
Hence, the layer is called a phospholipid bilayer, or sometimes a fluid mosaic membrane. Embedded within this membrane is a macromolecular structure called the porosome the universal secretory portal in cells and a variety of protein molecules that act as channels and pumps that move different molecules into and out of the cell. [2]
Until 1982, it was widely accepted that phospholipids and membrane proteins were randomly distributed in cell membranes, according to the Singer-Nicolson fluid mosaic model, published in 1972. [6] [18] However, membrane microdomains were postulated in the 1970s using biophysical approaches by Stier & Sackmann [19] and Klausner & Karnovsky. [20]
Integral membrane proteins function when incorporated into a lipid bilayer, and they are held tightly to the lipid bilayer with the help of an annular lipid shell. Because bilayers define the boundaries of the cell and its compartments, these membrane proteins are involved in many intra- and inter-cellular signaling processes.