C. Phospholipids 1. Phospholipids have a glycerol backbone, two fatty acids, a phosphate group, and a small hydrophilic group. They are important components of cell membranes, where the hydrophilic heads face toward the inner and outer surfaces and the hydrophobic tails face inward. D. Sterols and Their Derivatives 1. Sterols have a backbone of four carbon rings, but no fatty acids.
Cholesterol is a component of cell membranes in animals and can be modified to form sex hormones.
E. Waxes 1. Waxes are special molecules with fatty acid chains attached to alcohols. They confer extraordinary waterproofing qualities. Amino Acids and the Primary Structure of Proteins A. Proteins function as enzymes, in cell movements, as storage and transport agents, as hormones, as antidisease agents, and as structural material throughout the body. B. Structure of Amino Acids 1.