The cell membrane is primarily composed of phospholipids, proteins, carbohydrates, and other lipids such as cholesterol. Phospholipids form a bilayer that creates the basic structure of the membrane, with hydrophobic tails inward and hydrophilic heads outward. Proteins embedded in the membrane function as transporters and receptors. Carbohydrates attached to proteins or lipids help in cell recognition and adhesion. Cholesterol, a waxy lipid found interspersed within the membrane, contributes to membrane fluidity and stability. Cholesterol, which is an important component of cell membranes, also serves as the precursor molecule used to create steroid hormones. These steroid hormones include estrogens, testosterone, cortisol, and aldosterone, among others. The synthesis of steroid hormones begins with cholesterol, which is converted through several enzymatic steps in glands such as the adrenal glands and gonads to produce active hormones. In summary:

• Cell membranes are made up of phospholipids, proteins, carbohydrates, and cholesterol (a lipid).
• Cholesterol from cell membranes is the precursor used to synthesize steroid hormones, key regulators in the body.

This dual role of cholesterol in maintaining cell membrane structure and serving as a hormone precursor highlights its biological importance. If you want, I can provide more details on the synthesis pathways of steroid hormones or on the specific functions of membrane components. This information is supported by detailed biochemical explanations of cell membrane composition and hormone synthesis mechanisms.