Answer to Question #109711 in Biochemistry for kylie

Question

Classify lipids and give an example each.

Answer 1

А lipid is a biomolecule that is soluble in nonpolar solvents. Lipids have been classified into eight categories.

1. Fatty acids. They are made of a hydrocarbon chain that terminates with a carboxylic acid group; this arrangement confers the molecule with a polar, hydrophilic end, and a nonpolar, hydrophobic end that is insoluble in water. Example - linolenic acid.
2. Glycerolipids are composed of mono-, di-, and tri-substituted glycerols, the best-known being the fatty acid triesters of glycerol, called triglycerides. The three hydroxyl groups of glycerol are each esterified, typically by different fatty acids. Example: seminolipid
3. Phospholipids. The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid "tails" and a hydrophilic "head" consisting of a phosphate group. The two components are usually joined together by a glycerol molecule. The phosphate groups can be modified with simple organic molecules such as choline, ethanolamine or serine.Examples of glycerophospholipids found in biological membranes are phosphatidylcholine.
4. Sphingolipids are a complicated family of compounds[40] that share a common structural feature, a sphingoid base backbone that is synthesized de novo from the amino acid serine and a long-chain fatty acyl CoA, then converted into ceramides, phosphosphingolipids, glycosphingolipids and other compounds. Example: gangliosides.
5. Sterols, such as cholesterol.Sterols are steroids in which one of the hydrogen atoms is substituted with a hydroxyl group, at position 3 in the carbon chain. They have in common with steroids the same fused four-ring core structure.
6. Prenol lipids are synthesized from the five-carbon-unit precursors isopentenyl diphosphate and dimethylallyl diphosphate that are produced mainly via the mevalonic acid (MVA) pathway. Carotenoids as an example.
7. Saccharolipids describe compounds in which fatty acids are linked directly to a sugar backbone, forming structures that are compatible with membrane bilayers. Example: the acylated glucosamine.
8. Polyketides are synthesized by polymerization of acetyl and propionyl subunits. Example:  tetracyclines