Final answer:
Cholesterol molecules are components of cell membranes and affect the movement of phospholipids, contributing to membrane fluidity and flexibility.
Step-by-step explanation:
Carbon rings of cholesterol are involved in the structure and function of cellular membranes. Specifically, cholesterol molecules are an important component of the plasma membrane of cells where they interfere with the movement of phospholipids. This interaction plays a crucial role in maintaining the fluidity and flexibility of the membrane. Cholesterol is amphiphilic, like phospholipids, and its structure includes a polar head and a hydrophobic tail, which allow it to insert itself between phospholipid molecules within the plasma membrane bilayer.