This the inner leaflet that point towards the side of plasma. Now, if we take take a line and we draw a line that separates the membrane in half, like so, we'll see that this side is not the same as this side. These two leaflets are not identical. And that implies that the plasma membrane is asymmetric. So the two leaflets, the two sides of the membrane are structurally and functionally not the same. Now, what factors contribute to the asymmetry of the plasma membrane?