Cholesterol is mostly a nonpolar molecule. This characteristic arises from its molecular structure, which consists of four hydrocarbon rings and a hydrocarbon tail. While cholesterol does contain a small hydroxyl group (-OH) that is polar, the overall shape and composition of the molecule make it predominantly hydrophobic (nonpolar).
The nonpolar nature of cholesterol is significant because it allows it to integrate into cell membranes, where it plays a critical role in maintaining fluidity and structural integrity. Its ability to interact with both polar and nonpolar substances also makes it essential for various biological functions, including the formation of steroid hormones and bile acids.