Which of the following is an example of a transversion?

Options

A. Cytosine - guanine
B. Thymine - uracil
C. Adenine - guanine
D. Cytosine - thymine

Answer

To determine which of the following is an example of a transversion, we first need to understand what a transversion is in the context of DNA mutations.

### Step-by-Step Solution:

1. **Define Transversion**: A transversion is a type of point mutation where a purine base (adenine or guanine) is replaced by a pyrimidine base (cytosine or thymine), or vice versa. This means that if a purine is substituted for a pyrimidine or a pyrimidine for a purine, it is considered a transversion.

2. **Identify the DNA Bases**: The four bases of DNA are:
- Purines: Adenine (A) and Guanine (G)
- Pyrimidines: Cytosine (C) and Thymine (T)

3. **Analyze the Options**: Now, let's analyze the options provided to identify which one represents a transversion.
- **Option A**: Cytosine (C) to Guanine (G) - This is incorrect because both are purines.
- **Option B**: Thymine (T) to Uracil (U) - This is incorrect because T is a pyrimidine and U is also a pyrimidine.
- **Option C**: Adenine (A) to Guanine (G) - This is incorrect because both are purines.
- **Option D**: Cytosine (C) to Thymine (T) - This is incorrect because both are pyrimidines.

4. **Correct Example**: Since none of the options provided are correct examples of a transversion, we need to clarify that a true transversion would involve a change such as:
- Adenine (A) to Cytosine (C) or Thymine (T)
- Guanine (G) to Cytosine (C) or Thymine (T)

5. **Conclusion**: Based on the definitions and analysis, none of the options provided in the question represent a transversion. A valid example of a transversion would be A to C or G to T.