Question

At what level of structure do Myoglobin and Hemoglobin differ the most with respect to their function?

• A. Primary structure
• B. Tertiary Structure
• C. Quaternary Structure
• D. Secondary Structure

Hint:

Quaternary = Cooperative binding; Monomer (Myoglobin) = No cooperativity.

Answer 1

The Correct Option is C

Step 1: Concept
Myoglobin and hemoglobin are both oxygen-binding proteins, but they operate differently based on their structural complexity.

Step 2: Meaning
Myoglobin is a monomer (single polypeptide chain), whereas hemoglobin is a tetramer (four subunits).

Step 3: Analysis
The quaternary structure of hemoglobin allows for cooperativity (allosteric regulation), where the binding of one oxygen molecule increases the affinity for others. Myoglobin, lacking quaternary interactions, follows a simple hyperbolic binding curve.

Step 4: Conclusion
The functional difference in oxygen transport versus storage is primarily due to the quaternary structure. Final Answer: (C)