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The Fluid Mosaic Model ( S. J. Singer and Garth Nicolson 1972 ) ( fluid = phospholipids can change positions and proteins can float along like rafts on a lake) ( Mosaic = there are lots of different “rafts floating in the lake”: proteins, carbohydrates etc…).
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The Fluid Mosaic Model (S. J. Singer and Garth Nicolson 1972 ) (fluid = phospholipids can change positions and proteins can float along like rafts on a lake) (Mosaic = there are lots of different “rafts floating in the lake”: proteins, carbohydrates etc…) Images courtesy of google images
2 Main roles of the cellular membrane: 1. Maintain cell’s structure and enclose its contents 2. Maintain a different composition within a cell compared to its environment (through the movement of materials into and out of the cell).
The main features: Base composition: phospholipid bilayer: -Hydrophobic tails directed towards the center of the membrane -Hydrophilic heads point towards the fluid medium on either side of the membrane Images courtesy of google images
The mosaic: Protein channels: transport things into or out of the cell Protein receptors: Bind signal molecules like hormones that cause a shape change in the receptor, leading to a cellular response. Images courtesy of google images
Cholesterol: provide stability to the membrane by preventing it from becoming fluid at high temperatures. Images courtesy of google images
Carbohydrates: Are attached to proteins and involved in cell recognition (these are called glycoproteins) • Glycolipids are similar to glycoproteins and involved in cell recognition Images courtesy of google images
Integral proteins go from one side of the membrane through to the other Peripheral proteins loosely and temporarily attached to the outer regions of the membrane or to integral proteins. Can be involved in signalling. • Both of these help stabilize membranes and hold them in place by linking them to the cell’s cytoskeleton.
