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 need to analyze the options provided in the question.

### Step-by-Step Solution:

1. **Understanding Insulin**: Insulin is a hormone produced by the pancreas that plays a crucial role in regulating blood sugar levels.

2. **Analyzing the Options**:
- **Option 1: Insulin is an amino acid**: This statement is false. Insulin is not a single amino acid; it is composed of multiple amino acids.
- **Option 2: Insulin is a polypeptide**: This statement is true. Insulin is indeed a polypeptide made up of a chain of amino acids.
- **Option 3: Insulin is a carbohydrate**: This statement is false. Insulin is not a carbohydrate; it does not consist of sugar molecules.
- **Option 4: Insulin is a lipid**: This statement is also false. Insulin is not a lipid; it is a protein.

3. **Composition of Insulin**: Insulin consists of 51 amino acids arranged in two chains (an alpha chain with 21 amino acids and a beta chain with 30 amino acids). This confirms that insulin is a polypeptide.

4. **Conclusion**: The only true statement about insulin from the options given is that it is a polypeptide.

### Final Answer:
**Insulin is a polypeptide.**

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