Question

Bacterial DNA protects its own DNA from being cut up by the restriction enzymes present in the cell because _____________ .

• A. bacterial DNA has no recongition sequences
• B. some of the nucleotides have caps of methyl group
• C. recognition sequences are covered with proteins
• D. only foriegn DNA can activate the restriction enzymes

Answer 1

The correct option is B some of the nucleotides have caps of methyl group

Restriction enzymes provide a protective mechanism to the bacterial cell by cutting the foriegn DNA but the bacterial DNA is also prone to the action of these enzymes. Cutting its own DNA is prevented because some of the nucleotides of recognition sites have caps of methyl groups. They are methylated. So the enzymes do not have access to the recognition sites for their action.