A bacterium modifies its DNA by adding methyl groups to the DNA, It does so to

Options

A. Clone its DNA
B. Be able to transcribe many genes simultaneously
C. Turn its gene on
D. Protect its DNA from its own restriction enzyme

Answer

To answer the question, "A bacterium modifies its DNA by adding methyl groups to the DNA, It does so to," we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Methylation**:
- Methylation refers to the addition of methyl groups (–CH3) to DNA. In bacteria, this process is crucial for modifying their DNA structure.

2. **Role of Restriction Endonucleases**:
- Bacteria produce enzymes called restriction endonucleases that recognize specific DNA sequences and cut the DNA at those sites. This is a defense mechanism against foreign DNA, such as that from viruses.

3. **Protection of Bacterial DNA**:
- If the bacterial DNA contains the same specific sequences that the restriction endonucleases target, the enzymes would cut the bacterial DNA itself. To prevent this, bacteria add methyl groups to their own DNA at these specific sequences.

4. **Function of Methylation**:
- By methylating their DNA, bacteria ensure that their own DNA is not recognized and cut by their restriction enzymes. This modification acts as a protective mechanism, allowing the bacteria to defend themselves against foreign DNA while preserving their own genetic material.

5. **Conclusion**:
- Therefore, the primary reason a bacterium modifies its DNA by adding methyl groups is to protect its DNA from being cut by its own restriction endonucleases.

### Final Answer:
A bacterium modifies its DNA by adding methyl groups to protect its DNA from its own restriction endonucleases.

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