Which one brings about point mutation?

Options

A. 5- methyl cytosine
B. Guanine
C. Adenine
D. 5-Bromouracil.

Answer

To solve the question "Which one brings about point mutation?", we will analyze each option provided and determine which one is responsible for causing point mutations.

### Step-by-Step Solution:

1. **Understand Point Mutation**:
- Point mutation refers to a change in a single nucleotide in the DNA sequence. This can occur through various mechanisms, including substitutions, insertions, or deletions of nucleotides.

2. **Evaluate the Options**:
- **5-methylcytosine**: This is a modified form of cytosine that has a methyl group attached. While it plays a role in gene regulation, it does not directly cause point mutations.
- **Guanine**: This is one of the four main nucleobases in DNA. It is a normal component of DNA and does not cause mutations by itself.
- **Adenine**: Similar to guanine, adenine is also a standard nucleobase in DNA and does not induce mutations.
- **5-bromouracil**: This is a brominated derivative of uracil and acts as a base analogue. It can substitute for thymine during DNA replication.

3. **Mechanism of 5-bromouracil**:
- When 5-bromouracil is incorporated into DNA, it can pair with guanine instead of adenine during DNA replication. This mispairing can lead to a change in the DNA sequence, resulting in a point mutation.

4. **Conclusion**:
- Based on the analysis, the correct answer is **5-bromouracil**, as it is the only option that can cause point mutations by substituting for thymine and pairing incorrectly with guanine.

### Final Answer:
The correct answer is **5-bromouracil**.

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