Chapter 26: Lipids

Summary

Lipids are a heterogeneous class of naturally occurring organic substances grouped together not by the presence of a distinguishing functional group or structural feature, but rather on the basis of common solubility properties.  Lipids are all insoluble in polar solvents like water but highly soluble in the non-polar or weakly polar organic solvents, including ether, chloroform, benzene, and acetone.  In fact, these four solvents are often referred to as "lipid-solvents" or "fat-solvents".  Other biomolecules such as amino acids, proteins, carbohydrates, and nucleic acids are largely insoluble in these solvents.

Lipids are widely distributed in both animal and plant systems and perform a wide variety of functions. These include energy storage, structural components (e.g. cell membranes), vitamins, metabolism regulators (e.g. steroid hormones), and emulsifying agents.

Some common types of lipids discussed here are:

• fats and oils
• phospholipids
• prostaglandins
• terpenes
• steroids

• Sample problems

© Dr. Ian Hunt, Department of Chemistry