how many molecules of oxygen are bound to one molecule of haemoglobin

Options

A. one
B. two
C. three
D. four

Answer

To determine how many molecules of oxygen are bound to one molecule of hemoglobin, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Hemoglobin Structure**: Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen. Each hemoglobin molecule consists of four subunits, and each subunit contains a ferrous (Fe²⁺) ion.

2. **Binding Sites**: Each of the four ferrous ions in hemoglobin can bind to one molecule of oxygen (O₂). Therefore, the total number of oxygen molecules that can bind to one hemoglobin molecule is directly related to the number of ferrous ions present.

3. **Calculate Total Oxygen Binding**: Since there are four ferrous ions in one hemoglobin molecule, it can bind to four molecules of oxygen. This is represented by the formula for oxyhemoglobin, which is Hb4O8, indicating that four oxygen molecules are bound to one hemoglobin molecule.

4. **Conclusion**: Thus, the answer to the question is that one molecule of hemoglobin can bind to **four molecules of oxygen**.

### Final Answer:
One molecule of hemoglobin can bind to **four molecules of oxygen**.

---