The primary structural component of the cell membrane is phospholipids, which form a bilayer that provides the fundamental framework. This bilayer creates a semi-permeable barrier essential for maintaining cellular integrity and regulating the movement of substances in and out of the cell. Phospholipids have hydrophilic heads and hydrophobic tails, allowing the membrane to self-assemble and create a stable environment for membrane proteins. This arrangement is crucial in surgical contexts involving cell preservation and drug delivery systems. Cholesterol, proteins, and carbohydrates serve supportive or functional roles but do not form the basic membrane structure.

Reference: Molecular Biology of the Cell, Bruce Alberts, 6th Edition.