https://wikimd.org/index.php?action=history&feed=atom&title=Cell_membraneCell membrane - Revision history2026-05-14T18:43:09ZRevision history for this page on the wikiMediaWiki 1.44.2https://wikimd.org/index.php?title=Cell_membrane&diff=4967535&oldid=prevPrab at 03:35, 10 September 20232023-09-10T03:35:36Z<p></p>
<p><b>New page</b></p><div>The '''cell membrane''', sometimes referred to as the plasma membrane, acts as a barrier and gatekeeper for the cell. Its primary function is to encase the cell's contents and regulate the movement of substances in and out of the cell.<br />
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[[File:Cell membrane detailed diagram ua.svg|Cell membrane detailed diagram|thumb]]<br />
=== Structure ===<br />
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The cell membrane is primarily composed of a double layer of [[phospholipids]] called the lipid bilayer. Embedded within this bilayer are various proteins that serve multiple functions, from providing structural support to facilitating communication and transport.<br />
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* '''Lipid Bilayer''': This structure consists of two adjacent sheets of phospholipids, with the hydrophilic (water-attracting) "heads" facing outwards and the hydrophobic (water-repelling) "tails" facing inwards. This arrangement ensures that the cell membrane remains impermeable to many substances while allowing others to pass through.<br />
* '''Membrane Proteins''': These are proteins that are either partially or wholly embedded in the lipid bilayer. They play crucial roles in transport, signaling, and maintaining the cell's structural integrity.<br />
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=== Function ===<br />
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The cell membrane's primary function is to protect the cell from its surroundings and regulate the exchange of substances.<br />
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* '''Selective Permeability''': The cell membrane is selective about what it allows to pass through. While some molecules can freely pass across, others require specific transport proteins.<br />
* '''Signal Transduction''': The membrane has receptors that can recognize and respond to chemical signals, thus facilitating cell-to-cell communication.<br />
* '''Cell Adhesion''': Membrane proteins help cells adhere to other cells or to extracellular matrices, critical for tissue formation and stability.<br />
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=== Transport Mechanisms ===<br />
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The cell membrane controls the movement of substances using various mechanisms:<br />
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* '''Passive Transport''': Involves movement of substances down a concentration gradient without the use of energy. Examples include [[osmosis]] and [[diffusion]].<br />
* '''Active Transport''': Requires energy, usually in the form of ATP, to move substances against a concentration gradient. This is facilitated by pump proteins.<br />
* '''Endocytosis and Exocytosis''': Processes by which the cell ingests or expels large particles or volumes of fluid, respectively.<br />
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== Conclusion ==<br />
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The cell membrane is not just a passive barrier but a dynamic structure that plays an active role in various cellular processes. By selectively controlling what enters and leaves the cell, it maintains the cell's homeostasis and ensures its survival.<br />
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== See Also ==<br />
* [[Cell biology]]<br />
* [[Lipids]]<br />
* [[Proteins]]<br />
* [[Endocytosis]]<br />
* [[Exocytosis]]<br />
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{{Organelles}}<br />
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[[Category:Membrane biology]]<br />
[[Category:Organelles]]<br />
[[Category:Cell anatomy]]</div>Prab