Final answer:
Phospholipids are major constituents of the plasma membrane of animal cells. They are composed of fatty acid chains attached to a glycerol backbone. The phosphate group in phospholipids is negatively charged and hydrophilic.
Step-by-step explanation:
Phospholipids are major constituents of the plasma membrane, the outermost layer of animal cells. Like fats, they are composed of fatty acid chains attached to a glycerol backbone. Instead of three fatty acids attached as in triglycerides, however, there are two fatty acids and a modified phosphate group. The phosphate group is a small negatively charged molecule, while the fatty acid tail of the phospholipid is hydrophobic or repelled by water. These properties allow phospholipids to form a two-layer, or bilayer, cell membrane.