Assertion (A) : Restriction endonucleases recognise short pallindromic sequence and cut at specific sites
Reason (R) : When a restriction endonuclease acts on a pallindrome, it cleaves both the strands of DNA molecule.

Options

A. A and R both correct and R is explanation of A
B. A is correct and R is wrong
C. A and R are both correct but R is not correct explanation of A
D. A is wrong and R is correct.

Answer

To analyze the given assertion and reason, let's break down the information step by step.

### Step 1: Understand the Assertion
**Assertion (A)** states that "Restriction endonucleases recognize short palindromic sequences and cut at specific sites."

- **Explanation**: Restriction endonucleases are enzymes that can identify specific sequences of nucleotides in DNA. These sequences are often palindromic, meaning they read the same forwards and backwards. For example, a sequence like 5'-GAATTC-3' is palindromic because its reverse complement is also 5'-GAATTC-3'.

### Step 2: Understand the Reason
**Reason (R)** states that "When a restriction endonuclease acts on a palindrome, it cleaves both strands of the DNA molecule."

- **Explanation**: When restriction endonucleases bind to their specific palindromic sequences, they cleave the DNA at those sites. This cleavage occurs on both strands of the DNA helix, resulting in double-stranded breaks. This is crucial for various applications in molecular biology, including cloning and genetic engineering.

### Step 3: Evaluate the Relationship Between Assertion and Reason
Now, we need to determine whether both statements are correct and if the reason correctly explains the assertion.

- Both the assertion and the reason are indeed correct:
- The assertion correctly describes the function of restriction endonucleases.
- The reason accurately describes the action of these enzymes on palindromic sequences.

### Step 4: Determine if the Reason Explains the Assertion
While both statements are correct, the reason does not serve as an explanation for the assertion. The assertion describes what restriction endonucleases do (recognize and cut), while the reason describes how they do it (cleaving both strands). The reason does not explain why they recognize palindromic sequences or why they cut at specific sites.

### Conclusion
Based on the analysis:
- **Assertion (A)** is true.
- **Reason (R)** is true.
- However, **Reason (R)** does not explain **Assertion (A)**.

Thus, the correct answer is that both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.

### Final Answer
Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

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