Which one of the following palindromic base sequences in DNA can be easily cut at about the middle by some particular restriction enzyme?

Options

A. 5'-cgttcg-3'
3'-CCAAGC-5'
B. 5'-GAATTC-3'
3' -CTTAAG-5'
C. 5'-CTACTG-3'
3'-FTGCAA-5'
D. 5'-CACGTA-3'
3'-GCATAC-5'

Answer

To solve the question regarding which palindromic base sequence in DNA can be easily cut by a restriction enzyme, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Palindromic Sequences**:
- A palindromic sequence in DNA is a sequence of base pairs that reads the same forward and backward on complementary strands. For example, if one strand has the sequence 5'-GAATTC-3', the complementary strand will have 3'-CTTAAG-5'.

2. **Identify Restriction Enzymes**:
- Restriction enzymes, also known as endonucleases, recognize specific sequences in DNA and cut at or near these sites. Each restriction enzyme has a specific recognition site.

3. **Examine the Given Options**:
- The question provides several palindromic sequences. We need to analyze each one to see if they contain the recognition site for a restriction enzyme.

4. **Check Each Sequence**:
- **Option 1: GCTTCG**: This sequence does not contain the AT sequence, so it cannot be cut by a restriction enzyme.
- **Option 2: GAA TTC**: This sequence contains the AT sequence (AATT), which is recognized by the restriction enzyme EcoRI. This enzyme cuts between the G and A, making it a valid option.
- **Option 3: TA**: This is not a complete palindromic sequence and does not represent a restriction site.
- **Option 4: Another TA sequence**: Similar to the previous option, this does not represent a valid palindromic sequence for cutting.

5. **Conclusion**:
- The palindromic sequence that can be easily cut at about the middle by a restriction enzyme is **GAA TTC**.

### Final Answer:
The correct palindromic base sequence that can be easily cut by a restriction enzyme is **GAA TTC**.

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