Phospholipid Bilayer

The cell membrane is an extremely pliable structure composed primarily of back-to-back phospholipids (a “bilayer”).

 The cell membrane consists of two adjacent layers of phospholipids.

 The lipid tails of one layer face the lipid tails of the other layer, meeting at the interface of the two layers. The phospholipid heads face outward, one layer exposed to the interior of the cell and one layer exposed to the exterior (Figure 3.3). 

Cholesterol is also present, which contributes to the fluidity of the membrane, and there are various proteins embedded within the membrane that have a variety of functions.