Lipid/ja: Difference between revisions

Fatty acyls, a generic term for describing fatty acids, their conjugates and derivatives, are a diverse group of molecules synthesized by chain-elongation of an [[acetyl-CoA]] primer with [[malonyl-CoA]] or [[methylmalonyl-CoA]] groups in a process called [[fatty acid synthesis]]. They are made of a [[hydrocarbon chain]] that terminates with a [[carboxylic acid]] group; this arrangement confers the molecule with a [[chemical polarity|polar]], [[hydrophilic]] end, and a nonpolar, [[hydrophobic]] end that is [[insoluble]] in water. The fatty acid structure is one of the most fundamental categories of biological lipids and is commonly used as a building-block of more structurally complex lipids. The carbon chain, typically between four and 24 carbons long, may be saturated or [[unsaturated compound|unsaturated]], and may be attached to [[functional group]]s containing [[oxygen]], [[halogen]]s, [[nitrogen]], and [[sulfur]]. If a fatty acid contains a double bond, there is the possibility of either a ''cis'' or ''trans'' [[cis–trans isomerism|geometric isomerism]], which significantly affects the molecule's [[molecular configuration|configuration]]. ''Cis''-double bonds cause the fatty acid chain to bend, an effect that is compounded with more double bonds in the chain. Three double bonds in 18-carbon ''[[linolenic acid]]'', the most abundant fatty-acyl chains of plant ''thylakoid membranes'', render these membranes highly ''fluid'' despite environmental low-temperatures, and also makes linolenic acid give dominating sharp peaks in high resolution 13-C NMR spectra of chloroplasts. This in turn plays an important role in the structure and function of cell membranes. Most naturally occurring fatty acids are of the ''cis'' configuration, although the ''trans'' form does exist in some natural and partially hydrogenated fats and oils.