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Fatty acids are connected to this backbone, so that the lipid as a whole has a polar head and a non-polar tail. The lipid bilayer of the cell membrane consists of two layers of lipids, with the inner and outer surfaces of the membrane made up of the polar head groups, and the inner part of the membrane made up of the non-polar fatty acid tails.
The heads of glycolipids (glyco- stands for sugar) contain a sphingosine with one or several sugar units attached to it. The hydrophobic chains belong either to: two fatty acids (FA) – in the case of the phosphoglycerides, or; one FA and the hydrocarbon tail of sphingosine – in the case of sphingomyelin and the glycolipids.
The fatty chains in phospholipids and glycolipids usually contain an even number of carbon atoms, typically between 16 and 20. The 16- and 18-carbon fatty acids are the most common. Fatty acids may be saturated or unsaturated, with the configuration of the double bonds nearly always "cis".
[85] [86] The fatty acids may be subsequently converted to triglycerides that are packaged in lipoproteins and secreted from the liver. The synthesis of unsaturated fatty acids involves a desaturation reaction, whereby a double bond is introduced into the fatty acyl chain.
The latter can be distinguished again by means of the charge carrier. While in gangliosides sialic acids are found, sulfatides have a sulfate group. The structural similarity of most glycolipids is the so-called lactosylceramide, that is, a lactose disaccharide that is glycosidically bound to a ceramide.
Glycolipids provide the most extreme example of asymmetry in the lipid bilayer. [10] Glycolipids perform a vast number of functions in the biological membrane that are mainly communicative, including cell recognition and cell-cell adhesion. Glycoproteins are integral proteins. [2] They play an important role in the immune response and ...
General chemical structure of a monogalactosyl diacylglycerol (MGDG), a prevalent type of galactolipid. R 1 and R 2 are fatty chains. Galactolipids are a type of glycolipid whose sugar group is galactose. They differ from glycosphingolipids in that they do not have nitrogen in their composition. [1]
The primary saponifiable lipids are free fatty acids, neutral glycerolipids, glycerophospholipids, sphingolipids, and glycolipids. [ 1 ] By comparison, the non-saponifiable class of lipids is made up of terpenes, including fat-soluble A and E vitamins, and certain steroids, such as cholesterol.