Most are insoluble in water but soluble in nonpolar solvents. The definition excludes the mineral oils and other petroleum products obtained from fossil material. In living organisms lipids serve as the basis of cell membranes and as a form of fuel storage. Often lipids are found conjugated with proteins or carbohydrates, and the resulting substances are known as lipoproteins and lipopolysaccharides. The fat-soluble vitamins can be classified as lipids.
Liposomes are spherical vesicles formed by mixing lipids with water or water solutions.
The Columbia Encyclopedia, Sixth Edition. Click here to shop the Bartleby Bookstore .