Cell membranes are made of

Part of the cell membrane is a phospholipid bilayer, made of two layers of phospholipid molecules. However, the cell membrane also contains other macromolecules like membrane proteins, and carbohydrates.

According to research,

cellular membranes (e. g plasma membranes internal membranes):

are made of glycerophospholipids, molecules composed of glycerol, a phosphate group, and two fatty acid chains.

Glycerol is a three-carbon molecule that functions as the backbone of these membrane lipids.