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Chemistry LibreTexts

Lipid Fundamentals

Lipids are biomolecules which are soluble in organic non-polar solvents.


As lipids, fats and lipids are insoluble in water. Glycerides and waxes form a sub-group of compounds which have an ester as the major functional group and include: waxes, triglycerides, and phospholipids. Another diverse group of compounds which do not have any ester functional groups are also classified as lipids. Lipids without ester functional groups include: steroids, fatty acids, soaps, sphingolipids, and prostaglandins.

Lipid Functions

  1. Fats and lipids are important because they serve as energy source, as well as a storage for energy in the form of fat cells.
  2. Lipids have a major cellular function as structural components in cell membranes. These membranes in association with carbohydrates and proteins regulate the flow of water, ions, and other molecules into and out of the cells.
  3. Hormone steroids and prostaglandins are chemical messengers between body tissues.
  4. Vitamins A, D, E, and K are lipid soluble and regulate critical biological processes. Other lipids add in vitamin absorption and transportation.
  5. Lipids act as a shock absorber to protect vital organs and insulate the body from temperature extremes.

Steroids, Prostaglandins, and Sphingolipds

Lipid MiniTopics

  • Hydrogenation is used to convert unsaturated fats to saturated fats as in the making of margarine.
  • Olestra is a fat substitute which does not have any calories.
  • A micelle is a group of fatty acids, or lipids which clump together to the exclusion of water.
  • Detergents and Surfactants are related to soaps and have the same properties. Bile salts are also on this page.
  • Anabolic Steroids are synthetic steroids that are supposed to enhance the effects of testosterone. They are abused in sports.
  • Birth control pills are synthetic steroids.