Which of the following can relatively easily move laterally within the plasma membrane?

• A. Peripheral membrane proteins
• B. Phospholipids
• C. Cholesterol molecules
• D. Integral membrane proteins

Answer: (B)

Verified step by step guidance

1. Understand the structure of the plasma membrane: The plasma membrane is primarily composed of a phospholipid bilayer, cholesterol molecules, and proteins (both integral and peripheral). These components interact differently with the membrane, influencing their ability to move laterally.
2. Recognize the concept of lateral movement: Lateral movement refers to the ability of molecules to move side-to-side within the plane of the membrane without crossing it. This movement is influenced by the molecule's size, interaction with other components, and anchoring mechanisms.
3. Analyze phospholipids: Phospholipids are small, amphipathic molecules that form the bilayer structure of the membrane. They are not anchored and can move relatively freely within the bilayer, making lateral movement easy for them.
4. Evaluate cholesterol molecules: Cholesterol molecules are embedded within the phospholipid bilayer and interact with the fatty acid tails of phospholipids. While they can move laterally, their movement is more restricted compared to phospholipids due to these interactions.
5. Consider membrane proteins: Integral membrane proteins are embedded within the bilayer and often anchored to the cytoskeleton or extracellular matrix, limiting their lateral movement. Peripheral membrane proteins are attached to the surface of the membrane and may move laterally, but their movement is less free compared to phospholipids due to their interactions with other proteins or structures.