Number of iron atoms present in haemoglobin molecule is

Options

A. One
B. Two
C. Three
D. Four

Answer

To determine the number of iron atoms present in a hemoglobin molecule, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Hemoglobin**: Hemoglobin is a protein found in red blood cells (RBCs) that is essential for transporting oxygen from the lungs to the tissues and carbon dioxide from the tissues back to the lungs.

2. **Identify the Components of Hemoglobin**: Hemoglobin is composed of four polypeptide chains, which consist of two types: two alpha (α) subunits and two beta (β) subunits.

3. **Recognize the Role of Heme Groups**: Each of the four polypeptide chains is associated with a heme group. The heme group is a complex that contains iron.

4. **Determine the Iron Content**: Each heme group contains one iron (Fe) atom. Since there are four heme groups (one for each polypeptide chain), we can conclude that there is one iron atom per heme group.

5. **Calculate the Total Number of Iron Atoms**: Since there are four heme groups in total, and each heme group contains one iron atom, the total number of iron atoms in a hemoglobin molecule is:
\[ \text{Total Iron Atoms} = 4 \text{ (one from each heme group)} \]

6. **Select the Correct Answer**: Based on the calculation, the number of iron atoms present in a hemoglobin molecule is 4. Therefore, the correct answer is option D: 4.

### Final Answer:
The number of iron atoms present in a hemoglobin molecule is **4**.

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