Step 1: Understanding the Concept:
Saponification is the alkaline hydrolysis of an ester. Saponifiable lipids are those that contain ester bonds (usually between fatty acids and an alcohol like glycerol) which can be broken down to form soap (salts of fatty acids).
Step 2: Detailed Explanation:
1. Saponifiable Lipids: Triglycerides, Phospholipids, and Glycolipids all contain fatty acid chains attached via ester or amide bonds. When treated with a base (like NaOH), they produce soaps.
2. Non-saponifiable Lipids: These are lipids that do not contain fatty acids and cannot be hydrolyzed into soaps.
3. Cholesterol: It is a sterol (a complex steroid alcohol). Its structure consists of four fused hydrocarbon rings. Since it lacks ester-linked fatty acids, it cannot be saponified.
Step 3: Final Answer:
Cholesterol belongs to the non-saponifiable class of lipids.