In what way do the membranes of eukaryotic cells vary?

• A. All membranes have identical lipid and protein compositions.
• B. Only the plasma membrane contains phospholipids.
• C. Membranes differ only in their thickness, not in composition.
• D. Certain proteins and lipids are unique to each membrane type.

Answer: (D)

Verified step by step guidance

1. Understand the structure of eukaryotic cell membranes: Eukaryotic cells have various membranes, including the plasma membrane, nuclear envelope, endoplasmic reticulum, Golgi apparatus, and mitochondrial membranes. These membranes are primarily composed of a phospholipid bilayer with embedded proteins and other molecules.
2. Recognize the diversity of membrane composition: While all membranes share the basic structure of a phospholipid bilayer, the specific types of lipids and proteins embedded in the membrane vary depending on the function of the organelle or cell structure.
3. Consider the role of proteins: Membrane proteins are specialized for specific functions, such as transport, signaling, or enzymatic activity. For example, the plasma membrane contains receptor proteins for cell communication, while mitochondrial membranes contain proteins involved in energy production.
4. Examine the role of lipids: Different membranes may have unique lipid compositions. For instance, the plasma membrane contains cholesterol to maintain fluidity, while the inner mitochondrial membrane has a high concentration of cardiolipin, which is essential for mitochondrial function.
5. Conclude that membrane composition is functionally specialized: The variation in lipid and protein composition across different membranes allows each membrane to perform its specific role effectively, making certain proteins and lipids unique to each membrane type.