https://citizendium.org/wiki/index.php?title=Cell_membrane&feed=atom&action=historyCell membrane - Revision history2024-03-28T22:43:38ZRevision history for this page on the wikiMediaWiki 1.39.5https://citizendium.org/wiki/index.php?title=Cell_membrane&diff=27999&oldid=previmported>Caesar Schinas: Bot: Update image code2009-06-08T11:30:57Z<p>Bot: Update image code</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 06:30, 8 June 2009</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' comprises the outer surface of a [[cell (biology)|cell]] &mdash; a boundary that encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The unit structure of the phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' comprises the outer surface of a [[cell (biology)|cell]] &mdash; a boundary that encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The unit structure of the phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>{{Image|Cell_membrane_-1.JPG|left|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.}} <del style="font-weight: bold; text-decoration: none;">[[</del>Image<del style="font-weight: bold; text-decoration: none;">:</del>Cell membrane -2.JPG|right<del style="font-weight: bold; text-decoration: none;">|thumb</del>|710px|<del style="font-weight: bold; text-decoration: none;">{{#ifexist:Template:Cell membrane -2.JPG/credit|{{Cell membrane -2.JPG/credit}}<br/>|}}</del>"Cartoon of a typical cell membrane. Proteins are embedded in a matrix of phospholipid molecules. Several other membrane constituents such as glycolipids and cholesterol are also shown."<del style="font-weight: bold; text-decoration: none;">]]</del><br></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>{{Image|Cell_membrane_-1.JPG|left|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.}} <ins style="font-weight: bold; text-decoration: none;">{{</ins>Image<ins style="font-weight: bold; text-decoration: none;">|</ins>Cell membrane -2.JPG|right|710px|"Cartoon of a typical cell membrane. Proteins are embedded in a matrix of phospholipid molecules. Several other membrane constituents such as glycolipids and cholesterol are also shown."<ins style="font-weight: bold; text-decoration: none;">}}</ins><br></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td></tr>
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</table>imported>Caesar Schinashttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238099&oldid=previmported>Caesar Schinas: Bot: Update image code2009-06-08T09:10:44Z<p>Bot: Update image code</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 04:10, 8 June 2009</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' comprises the outer surface of a [[cell (biology)|cell]] &mdash; a boundary that encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The unit structure of the phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' comprises the outer surface of a [[cell (biology)|cell]] &mdash; a boundary that encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The unit structure of the phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">[[</del>Image<del style="font-weight: bold; text-decoration: none;">:</del>Cell_membrane_-1.JPG<del style="font-weight: bold; text-decoration: none;">|thumb</del>|left|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.<del style="font-weight: bold; text-decoration: none;">]] </del>[[Image:Cell membrane -2.JPG|right|thumb|710px|{{#ifexist:Template:Cell membrane -2.JPG/credit|{{Cell membrane -2.JPG/credit}}<br/>|}}"Cartoon of a typical cell membrane. Proteins are embedded in a matrix of phospholipid molecules. Several other membrane constituents such as glycolipids and cholesterol are also shown."]]<br></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{</ins>Image<ins style="font-weight: bold; text-decoration: none;">|</ins>Cell_membrane_-1.JPG|left|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.<ins style="font-weight: bold; text-decoration: none;">}} </ins>[[Image:Cell membrane -2.JPG|right|thumb|710px|{{#ifexist:Template:Cell membrane -2.JPG/credit|{{Cell membrane -2.JPG/credit}}<br/>|}}"Cartoon of a typical cell membrane. Proteins are embedded in a matrix of phospholipid molecules. Several other membrane constituents such as glycolipids and cholesterol are also shown."]]<br></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td></tr>
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</table>imported>Caesar Schinashttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238105&oldid=previmported>Milton Beychok: Added a link2009-02-04T01:59:09Z<p>Added a link</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 20:59, 3 February 2009</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Semi-permeable or selectively permeable membranes allow certain types of substances through the membrane and not others. Some forms of transport require no energy to perform- these mechanisms are called passive transport. The most common forms of passive transport are [[diffusion]] and [[osmosis]]. '''Diffusion''' occurs when a certain substance, such as an [[ion]], is more concentrated on one side of the membrane. If the membrane allows this ion through, then ions will move from the more concentrated side to the less concentrated side until reaching [[equilibrium]].</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Semi-permeable or selectively permeable membranes allow certain types of substances through the membrane and not others. Some forms of transport require no energy to perform- these mechanisms are called passive transport. The most common forms of passive transport are [[diffusion]] and [[osmosis]]. '''Diffusion''' occurs when a certain substance, such as an [[ion]], is more concentrated on one side of the membrane. If the membrane allows this ion through, then ions will move from the more concentrated side to the less concentrated side until reaching [[equilibrium]].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''[[Osmosis]]''' is the diffusion specifically of water across a membrane. A cell's [[tonicity]] indicates in which direction is the net flow of water and is based on the ionic content of the cell. A cell which is [[isotonic]] has an ionic concentration identical inside the membrane and out. Since the cell is at equilibrium, there is no [[concentration gradient]] and the flow of water in is equal to the flow of water out. A cell which is [[hypertonic]] has a higher concentration inside the cell than out. This causes a concentration gradient across the membrane which results in a net flow of water into the cell. A cell which is [[hypotonic]] has a lower concentration and therefore water will flow out of the cell. This tendency of a concentration gradient to cause a net flow of water is referred to as [[osmotic pressure]].</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''[[Osmosis]]''' is the diffusion specifically of water across a membrane. A cell's [[tonicity]] indicates in which direction is the net flow of water and is based on the ionic content of the cell. A cell which is [[isotonic]] has an ionic <ins style="font-weight: bold; text-decoration: none;">[[</ins>concentration<ins style="font-weight: bold; text-decoration: none;">]] </ins>identical inside the membrane and out. Since the cell is at equilibrium, there is no [[concentration gradient]] and the flow of water in is equal to the flow of water out. A cell which is [[hypertonic]] has a higher concentration inside the cell than out. This causes a concentration gradient across the membrane which results in a net flow of water into the cell. A cell which is [[hypotonic]] has a lower concentration and therefore water will flow out of the cell. This tendency of a concentration gradient to cause a net flow of water is referred to as [[osmotic pressure]].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>'''[[Facilitated diffusion]]''' is a passive form of transport whereby specific types of molecules are chemically encouraged to cross the membrane, but are not directional. That is, molecules will only flow down a concentration gradient, which is definitionally passive transport. This is accomplished by specialized proteins embedded in the surface called [[channels]] and [[carriers]]. Channels are gaps which allow the molecule to flow through them, and are sometimes gated (that is, are only open under certain conditions.) Carriers, or porters, chemically interact with the molecule to induce a [[conformational change]] which moves the molecule to the other side of the membrane.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>'''[[Facilitated diffusion]]''' is a passive form of transport whereby specific types of molecules are chemically encouraged to cross the membrane, but are not directional. That is, molecules will only flow down a concentration gradient, which is definitionally passive transport. This is accomplished by specialized proteins embedded in the surface called [[channels]] and [[carriers]]. Channels are gaps which allow the molecule to flow through them, and are sometimes gated (that is, are only open under certain conditions.) Carriers, or porters, chemically interact with the molecule to induce a [[conformational change]] which moves the molecule to the other side of the membrane.</div></td></tr>
</table>imported>Milton Beychokhttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238095&oldid=previmported>Pierre-Alain Gouanvic: /* Passive Transport */ of of2008-06-28T02:50:32Z<p><span dir="auto"><span class="autocomment">Passive Transport: </span> of of</span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Passive Transport===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Passive Transport===</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Semi-permeable or selectively permeable membranes allow certain types <del style="font-weight: bold; text-decoration: none;">of </del>of substances through the membrane and not others. Some forms of transport require no energy to perform- these mechanisms are called passive transport. The most common forms of passive transport are [[diffusion]] and [[osmosis]]. '''Diffusion''' occurs when a certain substance, such as an [[ion]], is more concentrated on one side of the membrane. If the membrane allows this ion through, then ions will move from the more concentrated side to the less concentrated side until reaching [[equilibrium]].</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Semi-permeable or selectively permeable membranes allow certain types of substances through the membrane and not others. Some forms of transport require no energy to perform- these mechanisms are called passive transport. The most common forms of passive transport are [[diffusion]] and [[osmosis]]. '''Diffusion''' occurs when a certain substance, such as an [[ion]], is more concentrated on one side of the membrane. If the membrane allows this ion through, then ions will move from the more concentrated side to the less concentrated side until reaching [[equilibrium]].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>'''[[Osmosis]]''' is the diffusion specifically of water across a membrane. A cell's [[tonicity]] indicates in which direction is the net flow of water and is based on the ionic content of the cell. A cell which is [[isotonic]] has an ionic concentration identical inside the membrane and out. Since the cell is at equilibrium, there is no [[concentration gradient]] and the flow of water in is equal to the flow of water out. A cell which is [[hypertonic]] has a higher concentration inside the cell than out. This causes a concentration gradient across the membrane which results in a net flow of water into the cell. A cell which is [[hypotonic]] has a lower concentration and therefore water will flow out of the cell. This tendency of a concentration gradient to cause a net flow of water is referred to as [[osmotic pressure]].</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>'''[[Osmosis]]''' is the diffusion specifically of water across a membrane. A cell's [[tonicity]] indicates in which direction is the net flow of water and is based on the ionic content of the cell. A cell which is [[isotonic]] has an ionic concentration identical inside the membrane and out. Since the cell is at equilibrium, there is no [[concentration gradient]] and the flow of water in is equal to the flow of water out. A cell which is [[hypertonic]] has a higher concentration inside the cell than out. This causes a concentration gradient across the membrane which results in a net flow of water into the cell. A cell which is [[hypotonic]] has a lower concentration and therefore water will flow out of the cell. This tendency of a concentration gradient to cause a net flow of water is referred to as [[osmotic pressure]].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''[[Facilitated diffusion]]''' is a passive form of transport whereby specific types of molecules are chemically encouraged to cross the membrane, but are not directional. That is, molecules will only flow down a concentration gradient, which is definitionally passive transport. This is accomplished by specialized proteins embedded in the surface called [[channels]] and [[carriers]]. Channels are gaps which allow the molecule to flow through them, and are sometimes gated (that is, are only open under certain conditions.) Carriers, or porters, chemically interact with the molecule to induce a [[conformational change]] which moves the molecule to the other side of the membrane. <del style="font-weight: bold; text-decoration: none;"> </del></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''[[Facilitated diffusion]]''' is a passive form of transport whereby specific types of molecules are chemically encouraged to cross the membrane, but are not directional. That is, molecules will only flow down a concentration gradient, which is definitionally passive transport. This is accomplished by specialized proteins embedded in the surface called [[channels]] and [[carriers]]. Channels are gaps which allow the molecule to flow through them, and are sometimes gated (that is, are only open under certain conditions.) Carriers, or porters, chemically interact with the molecule to induce a [[conformational change]] which moves the molecule to the other side of the membrane.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Active Transport===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Active Transport===</div></td></tr>
</table>imported>Pierre-Alain Gouanvichttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238093&oldid=previmported>Pierre-Alain Gouanvic: /* Membrane Permeability */ typo2008-06-28T02:49:40Z<p><span dir="auto"><span class="autocomment">Membrane Permeability: </span> typo</span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>An essential feature of any plasma membrane is the ability to transport <del style="font-weight: bold; text-decoration: none;">matertials </del>in and out of the cell.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>An essential feature of any plasma membrane is the ability to transport <ins style="font-weight: bold; text-decoration: none;">materials </ins>in and out of the cell.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Passive Transport===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Passive Transport===</div></td></tr>
</table>imported>Pierre-Alain Gouanvichttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238085&oldid=previmported>Anthony.Sebastian: test2008-06-27T23:53:34Z<p>test</p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td></tr>
</table>imported>Anthony.Sebastianhttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238097&oldid=previmported>Anthony.Sebastian: add another image perspective cell membrane2008-06-27T23:52:13Z<p>add another image perspective cell membrane</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' comprises the outer surface of a [[cell (biology)|cell]] &mdash; a boundary that encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The unit structure of the phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' comprises the outer surface of a [[cell (biology)|cell]] &mdash; a boundary that encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The unit structure of the phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Cell_membrane_-1.JPG|thumb|<del style="font-weight: bold; text-decoration: none;">center</del>|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.]]<br></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Cell_membrane_-1.JPG|thumb|<ins style="font-weight: bold; text-decoration: none;">left</ins>|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.<ins style="font-weight: bold; text-decoration: none;">]] [[Image:Cell membrane -2.JPG|right|thumb|710px|{{#ifexist:Template:Cell membrane -2.JPG/credit|{{Cell membrane -2.JPG/credit}}<br/>|}}"Cartoon of a typical cell membrane. Proteins are embedded in a matrix of phospholipid molecules. Several other membrane constituents such as glycolipids and cholesterol are also shown."</ins>]]<br></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td></tr>
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<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{|align="center"</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>See also: [http://www.johnkyrk.com/cellmembrane.html Animated essentials of cell membrane structure.]<ref name=kyrk2008>Kyrk J. (2007) [http://www.johnkyrk.com/cellmembrane.html Animated essentials of cell membrane structure.]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>See also: [http://www.johnkyrk.com/cellmembrane.html Animated essentials of cell membrane structure.]<ref name=kyrk2008>Kyrk J. (2007) [http://www.johnkyrk.com/cellmembrane.html Animated essentials of cell membrane structure.]</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>*Numerous beautiful and informative animations of cell membrane structure, properties and functions.</ref><br></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>*Numerous beautiful and informative animations of cell membrane structure, properties and functions.</ref><br></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|}</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td></tr>
</table>imported>Anthony.Sebastianhttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238091&oldid=previmported>Anthony.Sebastian: adding to intro2008-06-27T23:08:48Z<p>adding to intro</p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' <del style="font-weight: bold; text-decoration: none;">is </del>the outer surface of a [[cell (biology)|cell]] <del style="font-weight: bold; text-decoration: none;">and </del>encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' <ins style="font-weight: bold; text-decoration: none;">comprises </ins>the outer surface of a [[cell (biology)|cell]] <ins style="font-weight: bold; text-decoration: none;">&mdash; a boundary that </ins>encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The <ins style="font-weight: bold; text-decoration: none;">unit structure of the </ins>phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. <ins style="font-weight: bold; text-decoration: none;">The unit structure repeats in a parallel array that creates a three-dimensional enclosed fluid-filled surface. </ins>The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Cell_membrane_-1.JPG|thumb|center|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.]]<br></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Cell_membrane_-1.JPG|thumb|center|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.]]<br></div></td></tr>
</table>imported>Anthony.Sebastianhttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238089&oldid=previmported>Anthony.Sebastian: adding caption and link to animated cell membrane2008-06-20T21:09:06Z<p>adding caption and link to animated cell membrane</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:09, 20 June 2008</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' is the outer surface of a [[cell (biology)|cell]] and encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' is the outer surface of a [[cell (biology)|cell]] and encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Cell_membrane_-1.JPG|thumb|center|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Cell_membrane_-1.JPG|thumb|center|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.]]<ins style="font-weight: bold; text-decoration: none;"><br></ins></div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"><br></ins></div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>See:</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>See <ins style="font-weight: bold; text-decoration: none;">also</ins>: <ins style="font-weight: bold; text-decoration: none;">[http://www.johnkyrk.com/cellmembrane.html Animated essentials of cell membrane structure.]<ref name=kyrk2008>Kyrk J. (2007) [http://www.johnkyrk.com/cellmembrane.html Animated essentials of cell membrane structure.]</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">*Numerous beautiful and informative animations of cell membrane structure, properties and functions.</ref><br></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"><br></ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td></tr>
</table>imported>Anthony.Sebastianhttps://citizendium.org/wiki/index.php?title=Cell_membrane&diff=238087&oldid=previmported>Anthony.Sebastian: adding illustration2008-06-20T21:01:08Z<p>adding illustration</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:01, 20 June 2008</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' is the outer surface of a [[cell (biology)|cell]] and encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''cell membrane''' or '''plasma membrane''' is the outer surface of a [[cell (biology)|cell]] and encloses the contents of the cell. The cell membrane is composed of a [[phospholipid bilayer]] studded with [[protein|proteins]]. The phospholipid bilayer consists of two [[fatty acid]] chains that link to two of the three [[carbon|carbons]] of a molecule of [[glycerol]]. The third carbon is attached to a [[phosphate group]], which is in turn often attached to an [[alcohol]] or [[amine]]. The alcohol makes the phosphate-alcohol group, or head group, [[hydrophilic]]. The fatty acid chains, or tails, are [[hydrophobic]]. This results in the hydrophilic parts pointing towards each other and the hydrophilic parts pointing to the extra and intracellular areas. The fluid mosaic model of the plasma membrane holds that there are two types of proteins in the phospholipid bilayer. The first is called an [[integral protein]]. These proteins are generally fixed and cannot be removed without rupturing the cell. One type of integral protein called the [[transmembrane protein]] spans the membrane, so that its surface is both on the inside and outside of the cell. A second type of membrane protein is called a [[peripheral protein]] and can easily be removed from the membrane.</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Image:Cell_membrane_-1.JPG|thumb|center|700px|Public domain, courtesy Mariana Ruiz. The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.]]</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">See:</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Membrane Permeability==</div></td></tr>
</table>imported>Anthony.Sebastian