Bacteria produce many restriction endonucleases.What prevents these enzymes from degrading the host DNA?
A)A bacterium will produce endonucleases that recognize sequences that are not present in its own DNA.
B)The strong association between the histones and bacterial DNA prevent the endonucleases from acting on them.
C)The endonucleases are transported out of the cell so quickly they cannot significantly affect the host DNA.
D)The host DNA is specifically methylated and is therefore protected from cleavage.

Question

Quizplus · Accepted Answer

The host DNA is specifically methylated and is therefore protected from cleavage. This is because the bacteria will not methylate their own DNA, but they will methylate the host DNA. The restriction endonucleases recognize unmethylated DNA and therefore will not degrade the host DNA.

Bacteria Produce Many Restriction Endonucleases