Point mutation may occur due to

Options

A. alteration in DNA sequence
B. change in a single base pair of DNA
C. deletion of a segment of DNA
D. gain of a segment in DNA

Answer

### Step-by-Step Solution:

1. **Understanding Point Mutation**:
- Point mutation refers to a change in a single nucleotide base pair in the DNA sequence. This can involve the substitution of one base for another, the deletion of a base, or the addition of a base.

2. **Types of Changes**:
- **Substitution**: This is when one base is replaced by another. For example, if a guanine (G) is replaced by an adenine (A), this is a point mutation.
- **Deletion**: This refers to the loss of a base pair from the DNA sequence. However, this is not considered a point mutation as it affects more than one base.
- **Insertion**: This involves adding an extra base pair into the DNA sequence. Similar to deletion, this also affects more than one base and is not classified as a point mutation.

3. **Identifying the Correct Answer**:
- The question asks what causes point mutations. The most accurate answer is "change in a single base pair of DNA," as this directly describes the nature of point mutations.
- Other options like alteration in DNA sequence, deletion of a segment of DNA, or gain of a segment do not specifically describe point mutations, as they involve changes that affect multiple base pairs.

4. **Conclusion**:
- Therefore, point mutations occur primarily due to a change in a single base pair of DNA.