In addition to phospholipids what organic molecule is a part of cellular membranes?

In addition to phospholipids, cholesterol is a key organic molecule found in cellular membranes. Cholesterol helps to stabilize membrane fluidity, making membranes less permeable to very small water-soluble molecules that might otherwise pass freely through. It also contributes to the structural integrity of the membrane, allowing for proper functioning of membrane proteins and overall cellular health.