Who first discovered the restriction endonuclease?

Options

A. Smith
B. Jacob
C. Lwoff
D. Hounsfield

Answer

**Step-by-Step Solution:**

1. **Understanding Restriction Endonucleases**: Begin by defining what restriction endonucleases are. These are enzymes that can cut DNA at specific sequences. They are a type of endonuclease, which means they cut DNA strands internally rather than from the ends.

2. **Distinguishing Between Nucleases**: Differentiate between endonucleases and exonucleases. Endonucleases cut DNA in the middle of the strand, while exonucleases cut from the ends of the DNA strand.

3. **Identifying the First Discovery**: The question specifically asks who first discovered restriction endonucleases. This requires historical knowledge about the discovery of these enzymes.

4. **Citing the Discoverer**: The first restriction endonuclease was discovered by Hamilton Smith. Therefore, the answer to the question is Hamilton Smith.

5. **Final Answer**: Conclude with the final answer: "The first restriction endonuclease was discovered by Hamilton Smith."

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