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Chemical Constituents of Plasma membrane

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  Chemical Constituents of Plasma membrane A ll plasma membranes, regardless of source contains proteins and lipids. The ratio of proteins to lipids varies depending on the cell types. Lipid The basic structure of the plasma membrane is the lipid bilayer.This bilayer is composed of 2 leaflets of amphipathic liquid molecules, whose poar head groups are in contact with the intra or extracellular aqueous phase where as their non polar tails face each other, constituting the hydrophobic interior of the membrane.The primary physical forces for organising lipid bilayer are hydrophobic force of interactions. Apart from hydrophobic force, Van dar waals forces of interaction between the hydrocarbon tails favor close packing of tails.Finally there are electrostatic interaction and hydrogen bonding beteen the polar head groups and water molecules.All lipid molecules present in the lipid bilayer can be broadly classified into 3 classes l  Phospholipids l  Glycolipids l  Sterol P...
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Cell membrane /Plasma membrane

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    Plasma membrane or cell membrane Plasma membrane or cell membrane is a dynamic , fluid structure and forms external boundary of the cell. It acts as a selective permeable membrane and regulates molecular traffic across the boundary. Plasma membrane behaves as a capacitor. In absence of integral membrane proteins, plasma membrane have similar electrical properties. The non conductive lipid bilayer of the membrane separates the conductive extracellular and intracellular electrolyte solutions. This results in the separation of charge across the lipid bilayer and this charge separation   brings about an electrical potential difference across the bilayer which is referred to as membrane potential. Different models are: Overton model The Overton model, (1899)  proposed by Charles Overton, suggests that the plasma membrane is primarily composed of lipids, and its permeability is largely determined by the lipid solubility of substances. This model is based...
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