GAATTC is a recognition site for the restriction endonuclease

Options

A. EcoRI
B. EcoRII
C. Hindlll
D. BamHI

Answer

To solve the question regarding the recognition site GAATTC for a restriction endonuclease, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which restriction endonuclease recognizes the sequence GAATTC.

2. **Identify the Options**: The options provided are:
- A. EcoRI
- B. Echorii
- C. Hen 3
- D. Bam HI

3. **Recall Restriction Enzyme Functions**: Restriction endonucleases are enzymes that cut DNA at specific recognition sites. Each enzyme has a unique recognition sequence.

4. **Analyze the Recognition Sequence**: The sequence GAATTC is known to be a specific recognition site for certain restriction enzymes.

5. **Match the Recognition Sequence with the Options**:
- **EcoRI**: Recognizes and cuts at the sequence GAATTC.
- **Echorii**: This appears to be a misspelling or variation of EcoRI and is not a standard name for a restriction enzyme.
- **Hen 3**: This is not known to recognize GAATTC.
- **Bam HI**: Recognizes the sequence GGATCC, not GAATTC.

6. **Determine the Correct Answer**: Based on the recognition sequence, EcoRI is the correct answer as it specifically recognizes and cleaves the GAATTC sequence.

### Final Answer:
The correct restriction endonuclease that recognizes the sequence GAATTC is **A. EcoRI**.