Question

Which of the following are components of lipid raft in plasma membrane

• A. Cholesterol and sphingolipids
• B. Cholesterol and glycolipids
• C. Glycolipids and phospholipids
• D. Sphingolipids and glycolipids

Hint:

Think of a lipid raft as a "log jam" in the fluid river of the plasma membrane. The "logs" are the tightly packed sphingolipids, and the "water and small debris" holding them together is the cholesterol.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Lipid rafts are specialized microdomains within the cell membrane. They are more ordered and tightly packed than the surrounding bilayer, and they function as platforms for signal transduction and protein trafficking. Their unique properties are due to their specific lipid composition.
Step 2: Detailed Explanation:
The key components that define a lipid raft are:
Sphingolipids: These lipids, such as sphingomyelin and glycosphingolipids, have long, largely saturated fatty acyl chains that allow them to pack together tightly.
Cholesterol: This molecule acts as a "dynamic glue." It fits into the spaces between the sphingolipids, increasing the packing and ordering of the lipids, which is characteristic of the liquid-ordered phase found in rafts.
While glycolipids are a type of sphingolipid and are found in rafts, the most comprehensive and accurate description of the defining components is the combination of cholesterol and the broader class of sphingolipids. The general sea of the plasma membrane is primarily composed of phospholipids, which are less abundant within the rafts themselves.
Step 3: Final Answer:
The primary and defining components of lipid rafts are high concentrations of cholesterol and sphingolipids.