What is true about lnsulin ?

Options

A. It is an amino acid
B. It is a polypeptide
C. It is a carbohydrate
D. It is a lipid

Answer

To determine what is true about insulin, we can analyze the options provided:

1. **Identify the nature of insulin**: Insulin is a type of biomolecule. We need to classify it among the given options: amino acid, polypeptide, carbohydrate, or lipid.

2. **Understanding the structure of insulin**: Insulin is composed of amino acids linked together by peptide bonds. This means that it is not a single amino acid but rather a chain of amino acids.

3. **Classifying insulin**: Since insulin consists of a chain of amino acids, it is classified as a polypeptide. A polypeptide is a polymer of amino acids that are linked by peptide bonds.

4. **Function of insulin**: Insulin is a hormone that plays a critical role in regulating glucose levels in the bloodstream. It is secreted by the pancreas.

5. **Conclusion**: Based on the analysis, the correct statement about insulin is that it is a polypeptide.

### Step-by-Step Solution:
1. **Identify the options**: Amino acid, polypeptide, carbohydrate, lipid.
2. **Analyze the structure of insulin**: Insulin is made up of amino acids linked by peptide bonds.
3. **Classify insulin**: It is classified as a polypeptide.
4. **Understand the function**: Insulin regulates glucose levels in the blood and is secreted by the pancreas.
5. **Final answer**: Insulin is a polypeptide.