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The ester bond is formed between the carboxylate group of a fatty acid and the hydroxyl group of cholesterol. Cholesteryl esters have a lower solubility in water due to their increased hydrophobicity. Esters are formed by replacing at least one –OH (hydroxyl) group with an –O–alkyl (alkoxy) group.
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, [ 23 ] may be saturated or unsaturated , and may be attached to functional groups containing oxygen , halogens ...
An ester of a carboxylic acid. R stands for any group (typically hydrogen or organyl) and R ′ stands for any organyl group. In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (R ′). [1]
Membrane lipids are a group of compounds (structurally similar to fats and oils) which form the lipid bilayer of the cell membrane. The three major classes of membrane lipids are phospholipids, glycolipids, and cholesterol. Lipids are amphiphilic: they have one end that is soluble in water ('polar') and an ending that is soluble in fat ...
Monoglycerides are primarily used as surfactants, usually in the form of emulsifiers.Together with diglycerides, monoglycerides are commonly added to commercial food products in small quantities as "E471" (s.a. Mono- and diglycerides of fatty acids), which helps to prevent mixtures of oils and water from separating.
Glycerol has three hydroxyl functional groups, which can be esterified with one, two, or three fatty acids to form mono-, di-, and triglycerides. [2] These structures vary in their fatty acid alkyl groups as they can contain different carbon numbers, different degrees of unsaturation, and different configurations and positions of olefins.
The pancreatic lipase acts at the ester bond, hydrolyzing the bond and "releasing" the fatty acid. In triglyceride form, lipids cannot be absorbed by the duodenum. Fatty acids, monoglycerides (one glycerol, one fatty acid), and some diglycerides are absorbed by the duodenum, once the triglycerides have been broken down.
Three fatty acid chains are bonded to each glycerol molecule. Each of the three -OH groups of the glycerol reacts with the carboxyl end of a fatty acid chain (-COOH). Water is eliminated and the remaining carbon atoms are linked by an -O- bond through dehydration synthesis. Both the adipose tissue and the liver can synthesize triglycerides.