Insulin has 51 amino acids arranged in

Options

A. Single polypeptide
B. Two polypeptides of 21 and 30 amino acids
C. Two polypeptides of 25 and 26 amino acids
D. Three polypeptides having 15, 16 and 20 amino acids.

Answer

**Step-by-Step Solution:**

1. **Understanding Insulin Structure**: Insulin is a protein composed of amino acids. It is essential to know how these amino acids are arranged to understand the structure of insulin.

2. **Total Number of Amino Acids**: Insulin consists of a total of 51 amino acids.

3. **Polypeptide Chains**: Insulin is made up of two distinct polypeptide chains:
- **A Chain**: This chain contains 21 amino acids.
- **B Chain**: This chain contains 30 amino acids.

4. **Connecting the Chains**: The two polypeptide chains (A and B) are interconnected by two disulfide bridges, which are important for the stability of the insulin structure.

5. **Proinsulin Precursor**: Insulin is derived from a precursor molecule called proinsulin, which contains three chains (A, B, and C). The C chain, which has 33 amino acids, is removed during the conversion to active insulin.

6. **Conclusion**: Therefore, the correct arrangement of the amino acids in insulin is in two polypeptide chains of 21 and 30 amino acids.

**Final Answer**: Insulin has 51 amino acids arranged in 2 polypeptides of 21 and 30 amino acids.

---