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When FabB reacts with the cis-decenoyl intermediate, the final product after elongation will be an unsaturated fatty acid. [14] The two main unsaturated fatty acids made are Palmitoleoyl-ACP (16:1ω7) and cis-vaccenoyl-ACP (18:1ω7). [15] Most bacteria that undergo anaerobic desaturation contain homologues of FabA and FabB. [16]
Cis unsaturated fatty acids, however, increase cellular membrane fluidity, whereas trans unsaturated fatty acids do not. trans A trans configuration, by contrast, means that the adjacent two hydrogen atoms lie on opposite sides of the chain. As a result, they do not cause the chain to bend much, and their shape is similar to straight saturated ...
Vegetable oils and animal fats contain mostly triglycerides, but are broken down by natural enzymes into mono and diglycerides and free fatty acids and glycerol. Soaps are formed from the reaction of glycerides with sodium hydroxide. The product of the reaction is glycerol and salts of fatty acids.
Plant thylakoid membranes have the largest lipid component of a non-bilayer forming monogalactosyl diglyceride (MGDG), and little phospholipids; despite this unique lipid composition, chloroplast thylakoid membranes have been shown to contain a dynamic lipid-bilayer matrix as revealed by magnetic resonance and electron microscope studies. [59]
The double bonds in unsaturated fats can be converted into single bonds by reaction with hydrogen effected by a catalyst. This process, called hydrogenation, is used to turn vegetable oils into solid or semisolid vegetable fats like margarine, which can substitute for tallow and butter and (unlike unsaturated fats) resist rancidification.
Fatty acid degradation is the process in which fatty acids are broken down into their metabolites, in the end generating acetyl-CoA, the entry molecule for the citric acid cycle, the main energy supply of living organisms, including bacteria and animals.
In cellular metabolism, unsaturated fat molecules contain less energy (i.e., fewer calories) than an equivalent amount of saturated fat. The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty acid) the more susceptible it becomes to lipid peroxidation ( rancidity ).
Example of an unsaturated fat triglyceride. Left part: glycerol, right part from top to bottom: palmitic acid, oleic acid, alpha-linolenic acid. Chemical formula: C 55 H 98 O 6. Fatty acids, stored as triglycerides in an organism, are a concentrated source of energy because they contain little oxygen and are anhydrous.