Lipids are fats and fat-like substances. Previously, all lipids that were not actually fats were called lipoids; this term is outdated. Lipids are found in plants, animals, and microorganisms. The common property of lipids is insolubility in water and solubility in organic solvents (ether, benzene, chloroform , carbon tetrachloride, etc.). Lipids are divided into: 1) simple lipids, which include the actual fats (see) and waxes - esters of fatty acids and monohydric alcohols; 2) complex lipids, which, in addition to alcohols and fatty acids, contain other groups, for example, nitrogenous bases and phosphoric acid - phospholipids, or phosphatides (see), carbohydrate components (glycolipids), etc .; 3) other lipids - fatty acids, mono-and diglycerides, sterols (see), steroids , etc. Lipids are the most important energy reserve for organisms (see Fat metabolism). In addition, many of them play an important specific role, for example, in the structure of biological membranes. Steroids include certain hormones, vitamins, bile acids, and other biologically important substances. See also Lecithins, Cerebrosides .
Lipids (from the Greek. Lipos - fat) is a group of compounds that differ in their chemical structure, content in the body of animals, plants and microbes and biological role, but have some similar physicochemical properties (insolubility in water and aqueous saline solutions, solubility in organic solvents - benzene, chloroform, ether, alcohols, acetone). The term "lipids" is more general than the term "lipids", which includes a group of so-called fat-like substances (phosphatides, cerebrosides, waxes, etc.), but not true fats (triglycerides).Go
There are: 1) simple lipids, 2) complex lipids and 3) derivatives of lipids. Simple lipids include esters of fatty acids with various alcohols (true fats are esters of fatty acids with glycerol), waxes (esters of fatty acids and cetyl or other long-chain monohydric alcohols), esters of fatty acids and cholesterol (sterides and cholesterides), Vitamin A esters with palmitic or stearic acids, vitamin D esters. Complex lipids, in addition to esters of fatty acids and alcohols, contain other groups. Complex lipids (see) or phospholipids [fatty acid esters with glycerol, to which are attached various nitrogenous bases (choline, ethanolamine) or inositol and phosphoric acid] and glycolipids, or cerebroside (see), which include fatty acids (lignoceric, cerebronic, nerve), nitrogenous bases (sphingosine, dihydrosphingosine) and sugar (galactose). The glycolipids also include gangliosides (found in the gray matter of the brain; consist of sphingosine, stearic acid, neuraminic acid and hexoses) and sulfatides (cerebroside containing a sulfuric acid residue).
Derivatives of simple and complex lipids (or degradation products of the substances included in them), some free sterols and other compounds with physicochemical properties shared with lipids constitute the third group of lipids. These are diglycerides, monoglycerides and free fatty acids formed during the breakdown of fats, high molecular weight alcohols with a long straight chain, which are products of the splitting of waxes, alcohols containing ionic rings (vitamin A — alcohol and a number of carotenes), free sterols (cholesterol, vitamin D) , vitamins E and K, as well as a number of glucosides of plant steroids, in particular digitalis glucosides and saponins, and some intermediate products of sterol synthesis (hydrocarbon squalene).
From soybean oil, a lipid fraction consisting of glycerol, fatty acids, phosphoric acid, inositol, ethanolamine, galactose, arabinose and tartaric acid, and called liposol, has been isolated. Liposol is part of the brain and spinal cord.