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Phospholipids, a class of amphiphilic molecules, are the main components of biological membranes. The amphiphilic nature of these molecules defines the way in which they form membranes. They arrange themselves into lipid bilayers, by forming a sheet composed of two layers of lipids. Each layer forms by positioning their lypophilic chains to the ...
Glycerophospholipids are the main structural component of biological membranes. Their amphipathic nature drives the formation of the lipid bilayer structure of membranes. The cell membrane seen under the electron microscope consists of two identifiable layers, or "leaflets", each of which is made up of an ordered row of glycerophospholipid ...
[17] [18] Lecithin is a mixture of fats that contains phospholipids, including phosphatidylcholine, and the human body can convert phosphatidylcholine into choline. [19] [20] [21] The choline content in lecithin can vary, but it's found that phosphatidylcholine makes up about 25 to 35 percent of lecithin. Furthermore, only about 12 percent of ...
The lipid components of lipoproteins are insoluble in water. However, because of their detergent-like (amphipathic) properties, apolipoproteins and other amphipathic molecules (such as phospholipids) can surround the lipids, creating a lipoprotein particle that is itself water-soluble, and can thus be carried through body fluids (i.e., blood ...
Example of an unsaturated fat triglyceride (C 55 H 98 O 6). Left part: glycerol; right part, from top to bottom: palmitic acid, oleic acid, alpha-linolenic acid. Glycerolipids are composed of mono-, di-, and tri-substituted glycerols, [30] the best-known being the fatty acid triesters of glycerol, called triglycerides. The word "triacylglycerol ...
In biological membranes, the phospholipids often occur with other molecules (e.g., proteins, glycolipids, sterols) in a bilayer such as a cell membrane. [7] Lipid bilayers occur when hydrophobic tails line up against one another, forming a membrane of hydrophilic heads on both sides facing the water.
[4] [5] Anabolism is the biosynthesis phase of metabolism in which smaller simple precursors are converted to large and complex molecules of the cell. Anabolism has two classes of reactions. The first are dehydration synthesis reactions; these involve the joining of smaller molecules together to form larger, more complex molecules.
The best known sterol is cholesterol, which is found in humans. Cholesterol also occurs naturally in other eukaryote cell membranes. Sterols have a hydrophobic four-membered fused ring rigid structure, and a small polar head group. Cholesterol is bio-synthesised from mevalonate via a squalene cyclisation of terpenoids.