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

Options

A. 5'-GAATTC -3', 3'-CTTAAG-5'
B. 5'-CCAATG-3', 3'-CAATCC -5'
C. 5'-CATTAG-3', 3'-GATAAC-5'
D. 5'-GATACC-3', 3'-CCTAAG-5'

Answer

To determine which of the given options represents a palindromic sequence in DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of a Palindromic Sequence**:
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 3' to 5' direction on the complementary strand. This means that if you read the sequence from one end to the other, it should mirror itself.

2. **Examine the Options**:
We need to look at the provided options and analyze them to see if any of them fit the definition of a palindromic sequence.

3. **Analyze the First Option**:
Let's say the first option is a sequence: 5' - GAA TTC - 3'.
- When we read this from 5' to 3', we get GAA TTC.
- Now, we need to find the complementary sequence that would read in the opposite direction (3' to 5'). The complementary bases are:
- G pairs with C
- A pairs with T
- T pairs with A
- Therefore, the complementary sequence would be: 3' - CTT AAG - 5'.
- When read from 3' to 5', this gives us CTT AAG, which is the reverse of GAA TTC.

4. **Confirm the Palindromic Nature**:
Since the sequence GAA TTC reads the same forwards and backwards when considering the complementary strand, we confirm that this is indeed a palindromic sequence.

5. **Check Other Options**:
For the remaining options, we would repeat the same analysis. However, as mentioned in the video transcript, none of the other options will match the palindromic criteria.

6. **Conclusion**:
Based on the analysis, the first option is the only one that represents a palindromic sequence in DNA.

### Final Answer:
The correct answer is the **first option**.

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