Question

Discuss in detail two ways bacteria endonucleases distinguishes viral DNA from their own DNA to avoid self-destruction of their DNA.

Answer 1

-DNA methylation protects bacterial DNA from digestion from there own endonuclease.

-Bacteria have restriction enzymes, also called restriction endonuclease, which cut double stranded DNA at specific points into fragments. Interestingly, restriction enzymes don't divide (cleave) their own DNA.

-There are two specific reasons behind this. The first one is recognition sequence. It normally does not exist in the bacterial DNA.

- And the second one is the recognition sequence exist but the enzyme is methylation specific. Bacteria prevent their own DNA from cut down by the restriction enzyme through methylation of the restriction sites. Methylation of DNA is a very familiar way to modify DNA function and bacterial DNA is highly methylated. The overall process is called Restriction Modification System.