Adult human haemolgobin consists of

Options

A. 2 subunits `(alpha, alpha)`
B. 2 subunits `(beta, beta)`
C. 4 subunits `(2alpha, 2 beta)`
D. 3 subunits `(2 alpha, 1beta)`

Answer

To answer the question about what adult human hemoglobin consists of, we can break down the information step by step:

### Step-by-Step Solution:

1. **Understanding Hemoglobin Structure**:
- Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen. It has a complex structure known as quaternary structure.

2. **Identifying Polypeptide Chains**:
- The quaternary structure of hemoglobin is made up of multiple polypeptide chains. In the case of adult human hemoglobin, it consists of four polypeptide chains.

3. **Types of Chains**:
- Among these four chains, there are two types: alpha (α) and beta (β) chains. Specifically, adult human hemoglobin contains two alpha chains and two beta chains.

4. **Combining Chains**:
- These chains are held together by interactions that include the presence of iron (Fe) molecules, which are crucial for the hemoglobin's ability to bind and carry oxygen.

5. **Final Composition**:
- Therefore, the composition of adult human hemoglobin can be summarized as having two alpha (α) chains and two beta (β) chains, making the total four polypeptide chains.

6. **Conclusion**:
- Based on the above analysis, the correct answer to the question is that adult human hemoglobin consists of two alpha and two beta subunits.

### Answer:
Adult human hemoglobin consists of **two alpha (α) chains and two beta (β) chains**.

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