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The Fluid Mosaic Model

Structure of the Cell Membrane: The Fluid Mosaic Model

S.J. Singer and G.L. Nicolson proposed the Fluid Mosaic Model of the cell membrane in 1972. This model describes the structure of the cell membrane as a fluid structure with various protein and carbohydrate components diffusing freely across the membrane. The structure and function of each component of the membrane is provided in the table below. The table refers to the components of the cell membrane shown in the diagram in the figure below.

fluid-mosaic-model-biology

Image credit: Siyavula

Component StructureFunction
Phospholipid bilayerConsists of two layers of phospholipids. Each phospholipid has a polar, hydrophilic (water-soluble) head as well as a non-polar, hydrophobic (water-insoluble) tail.It is a semi-permeable structure that does not allow materials to pass through the membrane freely, thus protecting the intra and extracellular environments of the cell.
Membrane proteinsThese are proteins found spanning the membrane from the inside of the cell (in the cytoplasm) to the outside of the cell. Membrane proteins have hydrophilic and hydrophobic regions that allow them to fit into the cell membrane.Act as carrier proteins which control the movement of specific ions and molecules across the cell membrane.
GlycoproteinsConsist of short carbohydrate chains attached to polypeptide chains and are found on the extracellular regions of the membrane.These proteins are useful for cell-to-cell recognition.
GlycolipidsCarbohydrate chains attached to phospholipids on the outside surface of the membraneAct as recognition sites for specific chemicals and are important in cell-to-cell attachment to form tissues.

Video: About the The Fluid Mosaic Model of the Cell Membrane

Watch the video below to see an animation of the fluid mosaic of the cell membrane.

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