When a purine is replaced by a pyrimidine in a part of DNA the mutation so produced is called

Options

A. Transition
B. Transversion
C. Deletion
D. Reversal

Answer

To solve the question "When a purine is replaced by a pyrimidine in a part of DNA, the mutation so produced is called," we will analyze the options provided and identify the correct answer step by step.

### Step 1: Understand the Definitions
- **Purines**: These are nitrogenous bases that include adenine (A) and guanine (G).
- **Pyrimidines**: These are nitrogenous bases that include cytosine (C) and thymine (T).

### Step 2: Analyze the Options
1. **Transition**: This type of mutation occurs when a purine is replaced by another purine (A ↔ G) or a pyrimidine is replaced by another pyrimidine (C ↔ T). Therefore, this option does not fit our requirement since we are looking for a purine replaced by a pyrimidine.

2. **Transversion**: This type of mutation occurs when a purine is replaced by a pyrimidine or vice versa. For example, if adenine (A) is replaced by cytosine (C) or thymine (T), this is a transversion. This matches our requirement.

3. **Deletion**: This mutation involves the loss of a segment of DNA, which does not relate to the replacement of one base with another. Hence, this option is incorrect.

4. **Reversal**: This mutation involves a segment of DNA being cut and reinserted in the reverse orientation. This does not pertain to the replacement of bases, so this option is also incorrect.

### Step 3: Conclusion
After analyzing all options, the correct answer to the question is **Transversion**. This is the mutation that occurs when a purine is replaced by a pyrimidine in DNA.

### Final Answer
The mutation produced when a purine is replaced by a pyrimidine in a part of DNA is called **Transversion**.

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