Lipids (or fats)
Sterols
Sterols are lipids that have a structure which includes 4 rings fused together.
CHOLESTEROL
Sterols are present in both plants and animals. An important animal sterol is cholesterol (image above) . Cholesterol is very important because it makes part of the structure of cell membranes. It also participates in the formation of steroid hormones .
Steroids are a class of sterols. Many important hormones are steroids, including the ones that control sexual characteristics. An example is testosterone (below) :
Testosterone
Testosterone is present in males and females. It is also present in many animals. The role of testosterone in man includes the development of muscle, bone mass, and the growth of body hair.