Which of the following restriction endonuclease was discovered first

Options

A. Hind II
B. EcoRI
C. Bam HI
D. EcoR II

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which restriction endonuclease was discovered first among the options provided: EcoRI, BamHI, and EcoR2.

2. **Identifying Key Information**: The video transcript mentions that the first restriction enzyme was discovered in 1970 by scientists Hamilton O. Smith, Thomas Kelly, and Kent Willocks.

3. **Identifying the First Restriction Enzyme**: The transcript indicates that the first restriction enzyme was derived from the bacterium Haemophilus influenzae.

4. **Naming the Enzyme**: The transcript hints at the name of the first restriction enzyme, which is EcoRI.

5. **Conclusion**: Based on the information provided, the first restriction endonuclease discovered is EcoRI.

**Final Answer**: EcoRI

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