The protein haemoglobin found in humans can be described having a …………..structure.

Options

A. primary
B. secondary
C. tertiary
D. quaternary

Answer

### Step-by-Step Solution:

1. **Understanding Hemoglobin Structure**: Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen throughout the body.

2. **Identifying the Chains**: Hemoglobin consists of four polypeptide chains: two alpha (α) chains and two beta (β) chains. Each of these chains has a specific number of amino acids—141 in the alpha chains and 146 in the beta chains.

3. **Analyzing the Structure**: The arrangement of these chains and their interactions is crucial. The alpha and beta chains come together to form a functional protein.

4. **Defining the Quaternary Structure**: The term "quaternary structure" refers to a protein that is made up of more than one polypeptide chain. In the case of hemoglobin, the two alpha and two beta chains fit together to form a complex structure.

5. **Functionality of Hemoglobin**: Due to its quaternary structure, hemoglobin can bind to four molecules of oxygen, with each heme group in the chains capable of binding one oxygen molecule.

6. **Conclusion**: Therefore, the protein hemoglobin can be described as having a quaternary structure.

### Final Answer:
The protein hemoglobin found in humans can be described as having a **quaternary structure**.

---