But the non polar hydrophobic region shown in red of these lipids basically aggregate at the center of that cell membrane. And as we can see from the diagram, the non polar region of the membrane basically predominates and that makes the membrane predominantly non polar. And so what that implies is the cell membrane basically serves as a barrier for polar and charged molecules. If polar or charged molecules want to make their way into the cell or outside the cell, they have to use these channels. These pumps we call proteins, as we'll see in just a moment. So the lipid molecules are emphatic.