Insulin, a hormone is chemically

Options

A. a fat
B. a steroid
C. a carbohydrate
D. a protein

Explanation

**Step-by-Step Solution:**

1. **Understanding Insulin's Origin**: Insulin is produced by the beta cells of the pancreatic islets of Langerhans. This is important as it highlights the biological source of the hormone.

2. **Function of Insulin**: The primary function of insulin is to regulate blood sugar levels in the body. This establishes its role as a crucial hormone in metabolism.

3. **Chemical Structure of Insulin**: Insulin consists of two polypeptide chains, known as Chain A and Chain B. This indicates that insulin is a protein made up of amino acids.

4. **Composition of the Chains**: Chain A contains 21 amino acids, while Chain B contains 30 amino acids. This detail provides insight into the specific structure of the insulin molecule.

5. **Disulfide Bonds**: The two chains are linked together by disulfide bonds. This is a key feature of insulin's structure, as these bonds help maintain the integrity of the protein's three-dimensional shape.

6. **Conclusion**: Based on the information gathered, insulin is classified as a protein due to its polypeptide chain structure and the presence of amino acids.

**Final Answer**: Insulin, a hormone, is chemically a protein.

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