Bacteria protect themselves from viruses by fragmenting viral DNA with

Options

A. Exonuclease
B. Endonuclease
C. DNA ligase
D. Gyrase

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks how bacteria protect themselves from viruses, specifically by fragmenting viral DNA.

2. **Identifying the Mechanism**: Bacteria have a defense mechanism against viruses (bacteriophages) that involves cutting or fragmenting the viral DNA.

3. **Exploring the Options**: The options provided are:
- Exonuclease
- Endonuclease
- DNA
- Ligase
- Gyrase

4. **Defining the Terms**:
- **Exonuclease**: An enzyme that removes nucleotides from the ends of a DNA molecule.
- **Endonuclease**: An enzyme that cuts DNA at specific internal sites within the molecule.
- **DNA**: The genetic material itself.
- **Ligase**: An enzyme that joins two DNA strands together.
- **Gyrase**: An enzyme that introduces negative supercoils into DNA.

5. **Selecting the Correct Answer**: The correct answer is **endonuclease**. This enzyme allows bacteria to cut the viral DNA into fragments, preventing the virus from replicating.

6. **Conclusion**: Bacteria protect themselves from viruses by using endonucleases to fragment viral DNA.