Substitution of a purine with another type of purine is called

Options

A. Transversion
B. Transition
C. Inversion
D. Translocation

Answer

To solve the question regarding the substitution of a purine with another type of purine, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- First, we need to clarify what purines and pyrimidines are. Purines are nitrogenous bases that include adenine (A) and guanine (G). Pyrimidines include cytosine (C), thymine (T), and uracil (U).

2. **Define Substitution**:
- Substitution refers to a change in one nucleotide in the DNA sequence. This can involve replacing one base with another.

3. **Identify Types of Substitution**:
- There are two main types of substitutions:
- **Transition**: This is when a purine is substituted with another purine (A ↔ G) or a pyrimidine is substituted with another pyrimidine (C ↔ T).
- **Transversion**: This is when a purine is substituted with a pyrimidine (A or G ↔ C or T) or vice versa.

4. **Analyze the Question**:
- The question specifically asks about the substitution of a purine with another type of purine. Based on our definitions, this falls under the category of transition.

5. **Conclusion**:
- Therefore, the correct answer to the question is **transition**.

### Final Answer:
The substitution of a purine with another type of purine is called **transition**.

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