Questions: A bacterial strain is resistant to infection by a bacteriophage. Which statement is FALSE? Multiple Choice The bacterial host DNA is protected from restriction enzyme degradation by phosphorylation. The bacteria make restriction enzymes that degrade the virus genome. If the phage DNA was methylated, it would be protected from restriction enzyme degradation. The statements are ALL false. The bacterial host DNA is protected from restriction enzyme degradation by methylation.

The answer is the first one: The bacterial host DNA is protected from restriction enzyme degradation by phosphorylation.

Explanation for each option:

1. The bacterial host DNA is protected from restriction enzyme degradation by phosphorylation.

   • This statement is false. Bacterial host DNA is typically protected from restriction enzyme degradation by methylation, not phosphorylation. Methylation involves the addition of a methyl group to the DNA, which prevents the restriction enzymes from cutting the host DNA.

2. The bacteria make restriction enzymes that degrade the virus genome.

   • This statement is true. Bacteria produce restriction enzymes (also known as restriction endonucleases) that can cut foreign DNA, such as that from a bacteriophage, thereby protecting the bacterial cell from infection.

3. If the phage DNA was methylated, it would be protected from restriction enzyme degradation.

   • This statement is true. If the phage DNA were methylated in a manner similar to the host DNA, it would be protected from degradation by the host's restriction enzymes.

4. The statements are ALL false.

   • This statement is false. Not all the statements are false; some are true, as explained above.

5. The bacterial host DNA is protected from restriction enzyme degradation by methylation.

   • This statement is true. Methylation is the common mechanism by which bacterial host DNA is protected from its own restriction enzymes.

Summary: The false statement is the first one: "The bacterial host DNA is protected from restriction enzyme degradation by phosphorylation." The correct mechanism is methylation, not phosphorylation.