Lecture 10. Lipids

Lecture 10. Lipids - are the primary component of cell...

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Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form true polymers Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds The most biologically important lipids are fats , phospholipids , and steroids We will focus on phospholipids and cholesterol, the lipid components on biological membrane
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The synthesis and structure of a fat, or triacylglycerol The backbone consists of a 3-carbon molecule, glycerol. The –OH on each carbon is covalently linked to a fatty acid (long chain of hydrocarbons with a carboxyl group at one end The linkage is called an ester bond between the –OH and –COOH groups, releasing water
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Saturated fatty acids—all carbons linked by single covalent bonds Unsaturated F.A.—one or more double bonds in the hydrocarbon chain Whether the triacylglycerol is solid or liquid depends on its saturation state.
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Hydrophilic head WATER WATER Hydrophobic tail Phospholipids, which are similar to triacylglycerols,
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Unformatted text preview: are the primary component of cell membranes The structure of a phospholipid The 1-carbon of glycerol is bound to a phosphate, which, in turn, is bound to a hydrophilic head group. This makes the phospholipid amphipathic Hydrophilic head WATER WATER Hydrophobic tail Membranes form by self-assembly of a phospholipid bilayer in an aqueous environment Cholesterol, a steroid (and also amphipathic), is the second major lipid component in membranes HO CH 3 CH 3 H 3 C CH 3 CH 3 This hydroxyl group is the hydrophilic portion of cholesterol and is sufficient to make the molecule amphipathic 11_16_Cholesterol.jpg Membranes contain cholesterol wedged in among the phospholipids, with the tiny hydrophillic head group facing the aqueous environment Biomembranes are fluid. Two features of the lipids determine this fluidity: 1. the rigid rings in cholesterol 2. the kinks imposed by the double bonds in the unsaturated fatty acids...
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Lecture 10. Lipids - are the primary component of cell...

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