Published Online: 15 SEP 2009
Copyright © 2001 John Wiley & Sons, Ltd. All rights reserved.
How to Cite
Yeagle, P. L. 2009. Lipids. eLS. .
- Published Online: 15 SEP 2009
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Lipids are molecular building blocks for the most fundamental structures in biology, including the serum lipoproteins, the membranes of cells and cellular organelles and the membranes of enveloped viruses. Lipids provide a form of energy storage, like an electrical battery for an organism. Lipids are the metabolic precursors of hormones and signalling molecules in cells. Lipids regulate, often in specific ways, the functionality of biological membranes. A nearly uncountable catalogue of lipid molecules is found in nature, their individual structures imparting a wide variety of properties essential to the structures and functions of lipids in life.
The hydrophobic effect, which governs the behaviour of hydrocarbons in water, controls the structures formed by lipids.
Phospholipids, as well as many other lipids, spontaneously form bilayer structures when confronted with water, in accordance with the hydrophobic effect.
Lipid bilayers provide the fundamental architecture of biological membranes.
Lipid bilayers determine many of the properties of biological membranes including their limited permeability.
Thousands of different lipid species are found in biological membranes, but a classification system emphasizes the similarities in specific classes.
Unsaturation in the hydrocarbon chains of lipid bilayers supports the liquid crystal state of bilayers in biology, essential to the proper functioning of membrane enzymes.
Membrane bilayers are highly anisotropic and their dynamics determine further the properties of the membranes.
Although bilayers are inherently stable, defects in bilayer structure are required to initiate critical membrane fusion events.
Membrane lipids play biological roles in membrane biology as well as structural roles.
In biological membranes, lipids are generally asymmetrically distributed across the bilayer.
Some lipids are second messengers in intracellular signalling systems.