The question is, what exactly is the structure of our cell membrane? Now, the plasma membrane found in prokaryotes and eukaryotes is a phospholipid bilayer. The bilayer means we have two layers of phospholipids. We have an inner layer and the outer layer. Now, what exactly is a phospholipid? A phospholipid is a molecule that consists of a polar phosphate group attached to a nonpolar fatty acid via a group known as the glycerol group.