Which one of the following palindromic base sequences in DNA can be easily cut by EcoRI ?

Options

A. `5'………..CGTTCG……..3'
3'………..ATGGTA……….5'
B. `5'………..GATATG……..3'
3'………..CTACTA……….5'
C. `5'………..GAATTC……..3'
3'………..CTTAAG……….5'
D. `5'………..CACGTA……..3'
3'………..CTCAGT……….5'

Answer

To solve the question of which palindromic base sequence in DNA can be easily cut by EcoRI, we will follow these steps:

### Step-by-Step Solution:

1. **Understand EcoRI**: EcoRI is a restriction endonuclease that recognizes specific palindromic sequences in DNA and cuts between specific bases. The recognition sequence for EcoRI is "GAATTC".

2. **Define Palindromic Sequence**: A palindromic sequence in DNA is one that reads the same in both directions when looking at the complementary strands. For example, if one strand reads "GAATTC", the complementary strand should also read "GAATTC" when read in the 5' to 3' direction.

3. **Evaluate the Options**: We need to analyze the provided options to find out which one is a palindromic sequence that matches the EcoRI recognition site.

- **Option 1**: 5' Ct Cg Tt Cg 3' - This is not palindromic as the complementary strand does not match.
- **Option 2**: 5' Gatatg 3' - This is also not palindromic as the complementary strand reads differently.
- **Option 3**: 5' GAA TTC 3' - This is palindromic because the complementary strand also reads 5' GAA TTC 3'.
- **Option 4**: 5' CACGTA 3' - This is not palindromic since the complementary strand does not match.

4. **Identify the Correct Answer**: The only sequence that is palindromic and matches the EcoRI recognition site is option 3, "GAA TTC".

5. **Conclusion**: Therefore, the correct answer to the question is option 3: "GAA TTC".