Triglycerides
Lipids do not follow the same rules as closely as the other molecule groups. They are more easily characterized by two different groups: the steroids and the triglycerides. Triglycerides are made up of a glycerol molecule and three fatty acid chains. These chains are simply hydrocarbons that are very long, and thus can store very large amounts of chemical energy.
Steroids
The second kind of lipid, called a steroid, is a molecule that is derived from cholesterol. These are classified as lipids because they are hydrophobic. Most of these molecules act to go through the cell and nuclear membrane to act as a transcription factor for DNA.