what is the cell membrane made of?

The cell membrane is primarily made of a phospholipid bilayer, which includes mainly phospholipids and sterols (commonly cholesterol). It also contains various proteins and some carbohydrates. The phospholipids have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails, arranging themselves so the tails face inward, shielded from water, and the heads face outward toward the aqueous environments inside and outside the cell. Proteins are embedded in or attached to this bilayer, performing various functions such as transport and cell signaling. Cholesterol molecules interspersed in the membrane help maintain its fluidity. Carbohydrates, attached to proteins or lipids on the extracellular side, contribute to cell recognition and protection.