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 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 palmitic acid, a saturated fatty acid of 16 C. In it we can distinguish its carboxyl group, and its oleic acid, in which all the bonds of the skeleton are single bonds (from hence the denomination saturated). Below we can see the structure of coleic acid, 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. Linoleic acid, with two double bounds 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 three double bounds.
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This page was last modified 21:38, 17 October 2020.
