Which is pallindromic sequence :

Options

A. GAATTC
CTTAAG
B. GCAAAG
CGTTTC
C. ATCGGC
TAGCCG
D. ATCGCT
TAGCGA

Answer

### Step-by-Step Solution:

1. **Understanding Palindromic Sequences**: A palindromic sequence in DNA is a sequence of nucleotides that reads the same in both directions on complementary strands. This means that if you read one strand from 5' to 3', the complementary strand should read the same from 3' to 5'.

2. **Identifying Examples**: Common examples of palindromic sequences include those recognized by restriction enzymes. For instance, the EcoRI restriction enzyme recognizes the sequence GAATTC.

3. **Analyzing the Sequence**:
- For the sequence GAATTC:
- On one strand (5' to 3'): GAATTC
- On the complementary strand (3' to 5'): CTTAAG
- When you read the complementary strand from 5' to 3', it also reads GAATTC, confirming that it is palindromic.

4. **Evaluating Other Options**:
- Check other sequences provided in the options:
- If any sequence does not read the same in both directions, it is not palindromic.
- For example, if you have a sequence like ATC or AGC, they do not read the same backward.

5. **Conclusion**: After analyzing the sequences, the only palindromic sequence among the options is the one recognized by EcoRI, which is GAATTC.

### Final Answer:
The palindromic sequence is **GAATTC** (option number 1).

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