Identify the correct statement(s) in relation to RE's

Options

A. RE's show extreme specificity towards the base sequence in DNA strands
B. Each RE's recognises specific base sequence in DNA strands
C. No two different RE's will act on DNA at the same specific base sequence site
D. All

Answer

To identify the correct statement(s) in relation to restriction endonucleases (REs), let's analyze the statements provided:

### Step-by-Step Solution:

1. **Understanding Restriction Endonucleases (REs)**:
- Restriction endonucleases are enzymes that cut DNA at specific sequences. They are crucial in molecular biology for cloning and genetic engineering.

2. **Evaluating the First Statement**:
- The first statement claims that "the restriction endonuclease RE shows extreme specificity towards the base sequence in DNA."
- This statement is **incorrect**. While REs do recognize specific sequences, they do not exhibit "extreme specificity." They have a defined recognition sequence where they cut, but they can act on similar sequences.

3. **Evaluating the Second Statement**:
- The second statement asserts that "each restriction endonuclease recognizes a specific base sequence in the DNA strand."
- This statement is **correct**. Each RE has a unique recognition sequence that it identifies and binds to before making a cut.

4. **Evaluating the Third Statement**:
- The third statement states that "no two different restriction enzymes will act on the DNA of the same specific base sequence site."
- This statement is **incorrect**. It is possible for different restriction enzymes to recognize and act on the same DNA sequence. Therefore, this statement is not true.

5. **Evaluating the Fourth Statement**:
- The fourth statement claims "all of the above."
- Since not all previous statements are correct, this statement is also **incorrect**.

### Conclusion:
Based on the evaluations, the only correct statement is the second one: "each restriction endonuclease recognizes a specific base sequence in the DNA strand."

### Final Answer:
- The correct statement is: **"Each restriction endonuclease recognizes a specific base sequence in the DNA strand."**

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