Human haemoglobin is made up of

Options

A. Two polypeptide chains of four types
B. Two polypeptide chains of two types
C. Four polypeptide chains of four types
D. Four polypeptide chains of two types

Answer

**Step-by-Step Solution:**

1. **Understanding Hemoglobin Structure**: Human hemoglobin is a protein found in red blood cells (RBCs) that plays a crucial role in transporting oxygen and carbon dioxide throughout the body.

2. **Polypeptide Chains**: Hemoglobin is composed of four polypeptide chains. These chains are essential for its function and structure.

3. **Types of Polypeptide Chains**: The four polypeptide chains consist of:
- Two alpha chains (referred to as alpha 1 and alpha 2).
- Two beta chains (referred to as beta 1 and beta 2).

4. **Heme Group**: Each polypeptide chain contains a heme group, which is essential for binding oxygen. The heme group contains iron, which is critical for oxygen transport.

5. **Amino Acid Composition**: The alpha chains consist of approximately 141 amino acids each, while the beta chains consist of about 146 amino acids each.

6. **Final Composition**: Therefore, human hemoglobin is made up of four polypeptide chains (2 alpha and 2 beta), making it a tetrameric protein.

7. **Conclusion**: The correct answer to the question is that human hemoglobin is made up of four polypeptide chains of two types (2 alpha and 2 beta).

**Answer**: Human hemoglobin is made up of four polypeptide chains of two types: 2 alpha chains and 2 beta chains.

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