Final answer:
Lipids, particularly phospholipids, make up the majority of the cell membrane. They form a bilayer with embedded proteins and cholesterol, providing structure and allowing for cellular function and communication.
Step-by-step explanation:
The principal macromolecule that makes up the majority of the cell membrane is lipids, specifically phospholipids. The cell membrane, or plasma membrane, consists of a phospholipid bilayer, which forms a barrier that separates the interior of the cell from the external environment.
Cholesterol is also present within the bilayer, contributing to the membrane's fluidity, and proteins are embedded within the membrane, serving various functions such as transport and cell-to-cell communication. Carbohydrates, which are attached to proteins and lipids, are found on the membrane's exterior surface and play a role in cellular recognition.