BRAINCAKEFatty Acids and Glycerol
Triglycerides and phospholipids are built from two kinds of smaller molecule: glycerol and fatty acids.
Glycerol (propane-1,2,3-triol, C3H8O3) is a small alcohol with three carbon atoms, each carrying an –OH (hydroxyl) group. These three –OH groups are where fatty acids attach.
A fatty acid has a carboxyl group (–COOH) at one end attached to a long hydrocarbon chain, usually 14 to 22 carbon atoms long. It is often written as R–COOH, where R is the hydrocarbon tail. The carboxyl group is what reacts with glycerol; the tail is non-polar and hydrophobic.
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Key terms in this lesson
- hydrophobic
- Repelled by water; describes non-polar groups or molecules that cannot form hydrogen bonds with water.
More in Biological Molecules
- Test for Starch
- Glycogen
- Cellulose
- The Nature of Lipids
- Triglycerides
- Phospholipids
- Unit Membrane
- Test for Lipids
All 25 lessons in Biological Molecules · All Edexcel AS-level Biology topics