Cholesterol has a unique structure that includes four linked hydrocarbon rings forming the steroid structure. The hydrocarbon tail links to one end of the steroid and a hydroxyl group linked to other end. While the hydroxyl group is able to form hydrogen bonds with nearby carbonyl oxygen of phospholipid. Additionally, cholesterol is an amphipathic macromolecule because it has a water-soluble polar region that dissolves in water, but almost the entire is non-polar which does not dissolves in water. It is also embedded in bilayer and serves a variety of functions in the human body which includes such as regulating membrane fluidity in animals. It also helps maintain the integrity of these membranes, and plays a role in facilitating cell signaling
