LIPID MEMBRANE Meaning and
Definition
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A lipid membrane refers to a thin, flexible structure composed primarily of lipids that forms the boundary or outer barrier of cells and cellular compartments. Lipids are a class of organic molecules that are insoluble in water but soluble in organic solvents such as chloroform or ether. The lipid membrane is also commonly known as a cell membrane or plasma membrane.
The primary function of the lipid membrane is to separate the internal environment of a cell or cellular compartment from its external surroundings. It plays a vital role in maintaining the integrity and selective permeability of the cell, allowing the passage of certain molecules while preventing the movement of others. Moreover, the lipid membrane acts as a boundary that regulates the exchange of nutrients, waste products, and signaling molecules between the cell and its surroundings.
The lipid membrane is mainly composed of phospholipids, which are lipids with a phosphate group attached to them. These phospholipids form a bilayer arrangement, with the hydrophilic (water-loving) phosphate heads facing outwards, interacting with the aqueous environment, while the hydrophobic (water-repelling) fatty acid tails face inwards, forming a hydrophobic core. This structure provides the lipid membrane with its characteristic fluidity and flexibility, allowing it to carry out its vital functions.
In addition to phospholipids, the lipid membrane also contains other lipids such as cholesterol and glycolipids, as well as proteins and carbohydrates that are embedded within or attached to its surface. These components contribute to the diverse functions of the lipid membrane, including cell signaling, transport of molecules across the membrane, and maintaining cell shape and stability.
Etymology of LIPID MEMBRANE
The word "lipid" comes from the Greek word "lipos" meaning "fat" or "grease". The term "lipid" was coined in 1923 by the German biochemist Otto Rosenheim. "Membrane" comes from the Latin word "membrāna", which means "thin layer" or "film". Therefore, the term "lipid membrane" refers to a thin layer or film composed of lipids.
