AskDefine | Define phospholipids

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English

Noun

phospholipids
  1. Plural of phospholipid

Extensive Definition

Phospholipids are a class of lipids, and a major component of all biological membranes, along with glycolipids, cholesterol and proteins. Understanding of the aggregation properties of these molecules is known as lipid polymorphism and forms part of current academic research.

Amphipathic character

Due to its polar nature, the head of a phospholipid is hydrophilic (attracted to water); the lipophilic (or often known as hydrophobic) tails are not attracted to water. When placed in water, phospholipids form one of a number of lipid phases. In biological systems this is restricted to bilayers, in which the lipophilic tails line up against one another, forming a membrane with hydrophilic heads on both sides facing the water. This allows it to form liposomes spontaneously, or small lipid vesicles, which can then be used to transport materials into living organisms and study diffusion rates into or out of a cell membrane.
This membrane is partially permeable, capable of elastic movement, and has fluid properties, in which embedded proteins (integral or peripheral proteins) and phospholipid molecules are able to move laterally. Such movement can be described by the Fluid Mosaic Model, that describes the membrane as a mosaic of lipid molecules that act as a solvent for all the substances and proteins within it, so proteins and lipid molecules are then free to diffuse laterally through the lipid matrix and migrate over the membrane. Cholesterol contributes to membrane fluidity by hindering the packing together of phospholipids. However, this model has now been superseded, as through the study of lipid polymorphism it is now known that the behaviour of lipids under physiological (and other) conditions is not simple.

See also

References

  1. J.M.Berg, J.L. Tymoczko, and L. Stryer, Biochemistry. 5th ed. 2002, New York: W.H. Freeman. xxxviii, 974, [976] (various pages)
phospholipids in Bulgarian: Фосфолипид
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phospholipids in German: Phospholipide
phospholipids in Estonian: Fosfolipiidid
phospholipids in Spanish: Fosfolípido
phospholipids in French: Phosphoacylglycérol
phospholipids in Korean: 인지질
phospholipids in Croatian: Fosfolipidi
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phospholipids in Icelandic: Fosfólípið
phospholipids in Italian: Fosfolipide
phospholipids in Hebrew: פוספוליפיד
phospholipids in Luxembourgish: Phospholipid
phospholipids in Lithuanian: Fosfolipidai
phospholipids in Macedonian: Фосфолипид
phospholipids in Dutch: Fosfolipide
phospholipids in Japanese: リン脂質
phospholipids in Polish: Fosfolipidy
phospholipids in Portuguese: Fosfolípido
phospholipids in Russian: Фосфолипиды
phospholipids in Slovenian: Fosfolipid
phospholipids in Finnish: Fosfolipidi
phospholipids in Swedish: Fosfolipid
phospholipids in Thai: ฟอสโฟลิพิด
phospholipids in Turkish: Fosfolipit
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