In gene mutation adenine is replaced by guanine .It is known as

Options

A. Substitution
B. point mutation
C. Transition
D. Transversion

Answer

To solve the question regarding the gene mutation where adenine is replaced by guanine, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Identify the Type of Mutation**: The question states that adenine (A) is replaced by guanine (G). This indicates a change in one nucleotide base.

2. **Understand Substitution**: The term "substitution" refers to the replacement of one nucleotide base with another. In this case, adenine is being substituted with guanine.

3. **Differentiate Between Transition and Transversion**:
- **Transition**: This is a specific type of substitution where a purine is replaced by another purine (A ↔ G) or a pyrimidine is replaced by another pyrimidine (C ↔ T).
- **Transversion**: This is another type of substitution where a purine is replaced by a pyrimidine or vice versa (A or G ↔ C or T).

4. **Classify the Mutation**: Since adenine (a purine) is replaced by guanine (another purine), this mutation falls under the category of a transition.

5. **Conclusion**: Therefore, the mutation where adenine is replaced by guanine is specifically known as a "transition."

### Final Answer:
The mutation where adenine is replaced by guanine is known as a **transition**.

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