Haemoglobin is a

Options

A. Monomer
B. Dimer
C. Trimer
D. Tetramer

Answer

**Step-by-Step Solution:**

1. **Understanding Hemoglobin**: Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen from the lungs to the rest of the body and returning carbon dioxide from the body back to the lungs.

2. **Identifying the Structure of Hemoglobin**: Hemoglobin is composed of four subunits. Each of these subunits is a polypeptide chain that contributes to the overall structure and function of the protein.

3. **Classification of Hemoglobin**: Given that hemoglobin consists of four subunits, it is classified as a "tetramer." The term "tetramer" refers to a protein that is made up of four subunits.

4. **Function of Hemoglobin**: The primary function of hemoglobin is to bind oxygen molecules in the lungs and release them in tissues where oxygen is needed. This is facilitated by the iron-containing heme groups present in each subunit.

5. **Conclusion**: Therefore, the correct answer to the question "Hemoglobin is a..." is that hemoglobin is a "tetrameric protein."

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