Phospholipids are formed from four components: fatty acids, a negatively charged phosphate group, an alcohol and a backbone. Phospholipids with a glycerol backbone are known as glycerophospholipids or phosphoglycerides. There is only one type of phospholipid with a sphingosine backbone; sphingomyelin. Phospholipids are a major component of all biological cell membrane, along with glycolipids and cholesterol. ==Phosphoglycerides== In phosphoglycerides, the carboxyl group of each fatty acid is esterified to the hydroxyl groups on carbon-1 and carbon-2. The phosphate group is attached to carbon-3 by an ester link. This molecule, known as a phosphatidate, is present in small quantities in membranes, but is also a precursor for the other phosphoglycerides. ===Phosphatidyl choline===
Phosphatidyl choline is the major component of lecithin. ===Phosphatidyl ethanolamine===
Phosphatidyl ethanolamine is the major component of cephalin. ===Phosphatidyl inositol=== ===Phosphatidyl serine=== ===Diphosphatidyl glycerol=== ===Synthesis=== In phosphoglyceride synthesis, phosphatidates must first be activated. Phospholipids can be formed from an activated diacylglycerol or an activated alcohol. Phosphatidyl serine and phosphatidyl inositol are formed from a phosphoester linkage between the hydroxyl of an alcohol (serine or inositol) and cytidine diphosphodiacylglycerol (CDP-diacylglycerol). In the synthesis of phospatidyl ethanolamine, the alcohol is first phosphorylated by adenosine triphosphate and subsequently reacts with cytidine diphosphate (CDP) to form the activated alcohol. The alcohol then reacts with a diacylglycerol to form the final product. In mammals, phosphatidyl choline can be synthesized via two separate pathways; a series of reactions similar to phosphatidyl ethanolamine synthesis, and the methylation of phosphatidyl ethanolamine, which is catalyzed by phosphatidyl ethanolamine methyltransferase, an enzyme found in the liver. ==Sphingomyelin==
The backbone of sphingomyelin is sphingosine, an amino alcohol formed from palmitate and serine. The amino terminal is acylation with a by a long-chain acyl CoA to yield ceramide. Subsequent substitution of the terminal hydroxyl group by phosphatidyl choline forms sphingomyelin. Sphingomyelin is present in all eukaryote cell (biology) membranes, but is mainly present in cells of the nervous system. ==Amphiphatic character== Due to its polar nature, the head of a phospholipid is attracted to water (it is hydrophilic). The nonpolar head is not attracted to water and is said to be hydrophobic. When placed in water, phospholipids form a bilayer, where the hydrophobic tails line up against each other, and forms a membrane with hydrophilic heads on both sides extending out into the water. This allows it spontaneously to form liposomes, or small lipid vesicle (biology), 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, very flexible, and has fluid properties, in which embedded proteins and phospholipid molecules are constantly moving laterally across the membrane because of the forces generated by their vibrations. Such movement can be described by the Fluid Mosaic Model, which basically 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 basically free to diffuse laterally through the lipid matrix and migrate over the membrane. ==See also== *biochemistry *lipid *lipid bilayer *antiphospholipid syndrome ==References== # Berg, J.M., J.L. Tymoczko, and L. Stryer, ''Biochemistry''. 5th ed. 2002, New York: W.H. Freeman. xxxviii, 974, [976] (various pagings) Phospholipids
I've updated the page a little with some extra general information about phospholipids, although it looks like someone may need to create an article on the Fluid-Mosaic Model used to describe phospholipid movement in cell membranes. I'll leave it to the experts, I think, since I'm not that great at lipid Biochemistry - User:Agaricus
See other meanings of words starting from letter:
Words begining with Phospholipid:
Phospholipid
Phospholipid
Phospholipids
Phospholipids
Phospholipid_bilayer
Phospholipid_bilayers
Phospholipid_membrane
Phospholipid
Phospholipids are formed from four components: fatty acids, a negatively charged phosphate group, an alcohol and a backbone. Phospholipids with a glycerol backbone are known as glycerophospholipids or phosphoglycerides. There is only one type of phospholipid with a sphingosine backbone; sphingomyelin. Phospholipids are a major component of all biological cell membrane, along with glycolipids and cholesterol. ==Phosphoglycerides== In phosphoglycerides, the carboxyl group of each fatty acid is esterified to the hydroxyl groups on carbon-1 and carbon-2. The phosphate group is attached to carbon-3 by an ester link. This molecule, known as a phosphatidate, is present in small quantities in membranes, but is also a precursor for the other phosphoglycerides. ===Phosphatidyl choline===
Phosphatidyl choline is the major component of lecithin. ===Phosphatidyl ethanolamine===
Phosphatidyl ethanolamine is the major component of cephalin. ===Phosphatidyl inositol=== ===Phosphatidyl serine=== ===Diphosphatidyl glycerol=== ===Synthesis=== In phosphoglyceride synthesis, phosphatidates must first be activated. Phospholipids can be formed from an activated diacylglycerol or an activated alcohol. Phosphatidyl serine and phosphatidyl inositol are formed from a phosphoester linkage between the hydroxyl of an alcohol (serine or inositol) and cytidine diphosphodiacylglycerol (CDP-diacylglycerol). In the synthesis of phospatidyl ethanolamine, the alcohol is first phosphorylated by adenosine triphosphate and subsequently reacts with cytidine diphosphate (CDP) to form the activated alcohol. The alcohol then reacts with a diacylglycerol to form the final product. In mammals, phosphatidyl choline can be synthesized via two separate pathways; a series of reactions similar to phosphatidyl ethanolamine synthesis, and the methylation of phosphatidyl ethanolamine, which is catalyzed by phosphatidyl ethanolamine methyltransferase, an enzyme found in the liver. ==Sphingomyelin==
The backbone of sphingomyelin is sphingosine, an amino alcohol formed from palmitate and serine. The amino terminal is acylation with a by a long-chain acyl CoA to yield ceramide. Subsequent substitution of the terminal hydroxyl group by phosphatidyl choline forms sphingomyelin. Sphingomyelin is present in all eukaryote cell (biology) membranes, but is mainly present in cells of the nervous system. ==Amphiphatic character== Due to its polar nature, the head of a phospholipid is attracted to water (it is hydrophilic). The nonpolar head is not attracted to water and is said to be hydrophobic. When placed in water, phospholipids form a bilayer, where the hydrophobic tails line up against each other, and forms a membrane with hydrophilic heads on both sides extending out into the water. This allows it spontaneously to form liposomes, or small lipid vesicle (biology), 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, very flexible, and has fluid properties, in which embedded proteins and phospholipid molecules are constantly moving laterally across the membrane because of the forces generated by their vibrations. Such movement can be described by the Fluid Mosaic Model, which basically 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 basically free to diffuse laterally through the lipid matrix and migrate over the membrane. ==See also== *biochemistry *lipid *lipid bilayer *antiphospholipid syndrome ==References== # Berg, J.M., J.L. Tymoczko, and L. Stryer, ''Biochemistry''. 5th ed. 2002, New York: W.H. Freeman. xxxviii, 974, [976] (various pagings) Phospholipids
Phospholipid
I've updated the page a little with some extra general information about phospholipids, although it looks like someone may need to create an article on the Fluid-Mosaic Model used to describe phospholipid movement in cell membranes. I'll leave it to the experts, I think, since I'm not that great at lipid Biochemistry - User:Agaricus
See other meanings of words starting from letter:
P
PA | PB | PC | PD | PE | PF | PG | PH | PI | PJ | PK | PL | PM | PN | PO | PR | PS | PT | PU | PW | PX | PY | PZ |Words begining with Phospholipid:
Phospholipid
Phospholipid
Phospholipids
Phospholipids
Phospholipid_bilayer
Phospholipid_bilayers
Phospholipid_membrane
These materials are based on Wikipedia and licensed under the GNU FDL
YouTube.com videos better site than Turbo Tax 2007
