Lipids: structure and classification

Lipids. Lipids are organic biomolecules that always contain C, H and O. They can also contain N and P. Chemically, they constitute a heterogeneous group. However, all of them share the hydrocarbon nature of at least part of their molecule, which explains why they are hydrophobic or, in some cases, amphipathic substances. Fatty acids.- Fatty acids are commonly found as building blocks of lipids, or covalently bound to cofactors or carrier proteins. In nature, small amounts are also found in the free state. Fatty acids are simply organic acids that have a long hydrocarbon chain (the most common from 12 to 24 carbon atoms). In the window on the right we can see the molecular structure of , a saturated fatty acid of 16 C. In it we can distinguish its , and its , in which all the bonds of the skeleton are single bonds (from hence the denomination saturated). Below we can see the structure of , a 16 C monounsaturated fatty acid with a double bond between carbons 9 and 10 of the hydrocarbon chain. Natural monounsaturated fatty acids are mostly cis-unsaturated, given the configuration of the substituents around the mentioned double bond. Fatty acids can have more than one double bond, and are then called polyunsaturated. , with in cis configuration in the positions shown in the image, is one of them. There are also polyunsaturated fatty acids, such as linolenic acid, which have . Saponifiable lipids.- .- Zoom on . Waxes.- for instance . .- lipids composed of , , and a polar compound like . Sphingolipids.- all of them include in their structure the amino alcohol . Sphingosine bind to a fatty acid to yield , the common structural feature of all sphingolipids. Unsaponifiable lipids.- Terpenes.- they are polymers of the 5 carbon unsaturated hydrocarbon named (2-methyl-1,3 butadiene). Some terpenes are , , , , and . Steroids.- Some steroids are , and . is also a steroid. Eicosanoids.- They are derived from unsaturated 20 carbon fatty acid named . are a class of eicosanoids.

spinqualitylabelsall models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

See AlsoSee Also

• Lípidos: estructura y clasificación
• Gramicidin Channel in Lipid Bilayer / Canal de gramicidina en bicapa lipídica (Spanish)
• Lipid bilayers and gramicidin channel includes models of gel and liquid forms of bilayers. / Modelo de bicapa lipídica y canal de gramicidina

ReferencesReferences

• Molecular models in this page were created or modified from PDB files by Alejandro Porto using the tool JSME Molecular Editor [1]