Identify the polypeptide subunit present in the adult haemoglobin

Options

A. Two `alpha`-and two `beta`-subunits
B. Four `alpha`-subunits
C. Four `beta`-subunits
D. Three `alpha`-subunits and one `beta`-subunits.

Answer

### Step-by-Step Solution:

1. **Understanding Hemoglobin Structure**:
- Hemoglobin is a protein found in red blood cells (RBCs) that is responsible for transporting oxygen from the lungs to the rest of the body.

2. **Composition of Hemoglobin**:
- Hemoglobin is a tetrameric protein, meaning it is composed of four polypeptide subunits.

3. **Identifying the Subunits**:
- In adult hemoglobin (also known as hemoglobin A), the structure consists of two types of polypeptide chains:
- **Alpha (α) Chains**: There are 2 alpha chains.
- **Beta (β) Chains**: There are 2 beta chains.

4. **Conclusion**:
- Therefore, the polypeptide subunits present in adult hemoglobin are **2 alpha (α) and 2 beta (β) subunits**.

### Final Answer:
The correct answer is **2α and 2β subunits**.

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