In gene mutations when a purine is substitde by another purine it is called as

Options

A. transformation
B. translocation
C. transduction
D. transition

Answer

To solve the question about gene mutations where a purine is substituted by another purine, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about a specific type of gene mutation where one purine base is replaced by another purine base.

2. **Identifying Purines**: In DNA, the purine bases are adenine (A) and guanine (G). Any mutation that involves the substitution of one purine with another purine falls under a specific category.

3. **Exploring the Options**: The options provided are:
- Transformation
- Translocation
- Transduction
- Transition

4. **Defining Each Option**:
- **Transformation**: This refers to the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material. This does not specifically relate to purine substitution.
- **Translocation**: This involves a chromosomal abnormality where a segment of a chromosome breaks off and attaches to another chromosome. This is not related to the substitution of purines.
- **Transduction**: This is the process by which foreign DNA is introduced into a cell by a virus. Again, this does not pertain to purine substitution.
- **Transition**: This is the specific term used when one purine is substituted by another purine (e.g., A to G or G to A).

5. **Conclusion**: Based on the definitions and explanations of each option, the correct answer to the question is **Transition**.

### Final Answer:
In gene mutations, when a purine is substituted by another purine, it is called a **Transition**.

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