Which one of the following represents a palindromic sequence in DNA ?

Options

A. `{:(5' - "CATTAG" -3'),(3' - "GATTAAC"-5'):}`
B. `{:(5' - "GATACC" -3'),(3' - "CCTAAG"-5'):}`
C. `{:(5' - "GAATTC" -3'),(3' - "CTTAAG"-5'):}`
D. `{:(5' - "CCAATG" -3'),(3' - "GAATCC"-5'):}`

Answer

To determine which sequence represents a palindromic sequence in DNA, we need to understand what a palindromic sequence is. A palindromic sequence in DNA is one that reads the same in the 5' to 3' direction on one strand as it does in the 5' to 3' direction on the complementary strand.

### Step-by-Step Solution:

1. **Understand the Definition of Palindromic Sequence**:
- A palindromic sequence in DNA is a sequence that is identical when read from the 5' end to the 3' end on one strand and from the 3' end to the 5' end on the complementary strand.

2. **Analyze Each Given Sequence**:
- **Sequence 1**: G A T T A G G A A
- 5' to 3' on one strand: G A T T A G G A A
- 3' to 5' on the complementary strand: T A A T C C T T
- Not the same, so this is NOT palindromic.

- **Sequence 2**: G A T G A T
- 5' to 3' on one strand: G A T G A T
- 3' to 5' on the complementary strand: C T A C T A
- Not the same, so this is NOT palindromic.

- **Sequence 3**: G A A T T C G A A T T C
- 5' to 3' on one strand: G A A T T C
- 3' to 5' on the complementary strand: C T T A A G
- This reads the same in both directions, making it palindromic.

- **Sequence 4**: C C C C T A
- 5' to 3' on one strand: C C C C T A
- 3' to 5' on the complementary strand: G G G G A T
- Not the same, so this is NOT palindromic.

3. **Conclusion**:
- The only sequence that is palindromic is **Sequence 3: G A A T T C G A A T T C**.

### Final Answer:
The palindromic sequence in DNA is **G A A T T C G A A T T C**.