And so these two chains basically extend along this direction, as shown in this pictorial representation. And this is a region that will be found deep inside that cell membrane interacting with the non polar regions of those nearby phospholipid molecules. And this is a section that will basically interact with the aqueous environment and with the heads, the hydrophilic heads of those nearby phospholipid molecules. Now, let's move on to cholesterol molecules. So, cholesterol molecules actually have a very special shape and that's because cholesterol molecules are actually steroid molecules. And what that means is they contain a four ring structure as shown in the following diagram.