The first human hormone produced by recombinant DNA technology is :

Options

A. Insulin
B. Estrogen
C. Thyroxine
D. Progesterone

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the first human hormone that was produced using recombinant DNA (rDNA) technology.

2. **Identifying the Hormone**: The first human hormone produced using rDNA technology is insulin. This hormone is crucial for regulating blood sugar levels in the body.

3. **Production of Insulin**:
- In the human body, insulin is produced by the beta cells located in the islets of Langerhans in the pancreas.
- Insulin is initially synthesized as a precursor molecule known as pro-insulin, which consists of an A chain and a B chain connected by a C-peptide chain.

4. **Conversion to Active Insulin**:
- The pro-insulin undergoes a conversion process where the C-peptide chain is removed.
- After the removal of the C-peptide, a disulfide bond forms between the A and B chains, resulting in the active form of insulin.

5. **Recombinant DNA Technology**:
- In the context of rDNA technology, scientists isolated the genes responsible for the A and B chains of insulin.
- These genes were then introduced into a bacterial host, such as E. coli, allowing the bacteria to produce insulin directly rather than pro-insulin.

6. **Conclusion**: Therefore, the answer to the question is insulin, which was the first human hormone produced through recombinant DNA technology.

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