Cell membrane lipid bilayer, illustration - stock illustration

Phospholipid bilayer. Computer illustration of the phospholipid bilayer that forms the membrane around all living cells. The cell membrane is made of phospholipid molecules. The molecules line up in two sheets, with the hydrophilic tails projecting inward and their polar head groups projecting outwards. The hydrophilic surface on both sides of the membrane is the point of contact for molecules leaving or entering the cell