Question

Lipid rafts are composed of

• A. Cholesterol and cardiolipin
• B. Sphingolipid and cardiolipin
• C. Sphingolipid and cholesterol
• D. Cholesterol but no sphingolipid

Hint:

Lipid rafts = cholesterol + sphingolipids. Cardiolipin is mitochondrial, not membrane raft-associated.

Answer 1

The Correct Option is C

Step 1: Understand what lipid rafts are.
Lipid rafts are microdomains within the plasma membrane that are rich in specific lipids and proteins. They serve as platforms for cellular processes like signaling, protein sorting, and membrane trafficking.

Step 2: Composition of lipid rafts.
Lipid rafts are enriched in:

• Cholesterol: Provides stability and reduces fluidity in the membrane.
• Sphingolipids: Including sphingomyelin and glycosphingolipids, which form tightly packed, ordered regions.

Step 3: Cardiolipin relevance.
Cardiolipin is primarily found in the inner mitochondrial membrane, not in plasma membrane lipid rafts. Hence, options containing cardiolipin are incorrect in this context.

Step 4: Evaluate the options.
Option (1): Incorrect — Cardiolipin is not part of lipid rafts.
Option (2): Incorrect — Same reason; includes cardiolipin.
Option (3): Correct — Matches the known composition of lipid rafts.
Option (4): Incorrect — Sphingolipids are a key component and cannot be excluded.