Question

How do bacterial cells protect their own DNA from restriction endonuclease?

• A. Methylation of the DNA at sites that are recognised by restriction enzymes
• B. They do not produce restriction enzymes
• C. Acetylation of the DNA at sites that are recognised by restriction enzymes
• D. Deletion of all recognition sites from their genome

Answer 1

The correct option is A Methylation of the DNA at sites that are recognised by restriction enzymes

Restriction enzymes are produced in bacteria to protect itself from viruses. These enzymes recognise foreign DNA and cleave it at specific sites. Bacteria are protected from their own restriction enzyme due to methylation of DNA at sites that are recognised by restriction enzymes. Methylation of DNA protects bacteria’s DNA from their own restriction enzymes.

The figure below shows the action of restriction enzyme, EcoR I, on (a) unmethylated DNA and (b) methylated DNA.