If the carbons are double-bonded to each other at one or more points, the fatty acid is said to be unsaturated . Examples are peanut oil, corn oil, olive oil, etc. When glycerol and 3 fatty acid chains are combined, a triglyceride or fat molecule is formed. Fats are important molecules for storing energy. There is twice as much energy in a gram of fat as in a gram of sugar.
Phospholipids are lipids which contain attached phosphate groups.
Some of the phopholipids are better known as lecithins. Lecithins are found in cell membranes and also help in the emulsification of fats. Steroids are arranged as interlocking rings of carbon. They often serve as hormones such as estradiol, progesterone, testosterone, cortisol , etc. Cholesterol is also a steroid made in our body and forms part of the cell membrane .