AP BIOLOGY

Detailed explanation-1: -Approximate Lipid Compositions of Different Cell Membranes. Four major phospholipids predominate in the plasma membrane of many mammalian cells: phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin. The structures of these molecules are shown in Figure 10-12.

Detailed explanation-2: -Cell membranes are composed primarily of fatty-acid-based lipids and proteins. Membrane lipids are principally of two types, phospholipids and sterols (generally cholesterol).

Detailed explanation-3: -Phospholipids are able to form cell membranes because the phosphate group head is hydrophilic (water-loving) while the fatty acid tails are hydrophobic (water-hating). They automatically arrange themselves in a certain pattern in water because of these properties, and form cell membranes.