What are the molecules that make up the majority of the membrane

Phospholipid Bilayer. The simple or basic building blocks of a cell membrane are phospholipids. Phospholipids contain a hydrophobic end, which is insoluble in water, made up of two fatty acid chains of nonpolar molecules such as carbons and hydrogens. The other end is hydrophilic, which is soluble in water, and contains polar phosphate molecules.