Q. Restriction-modification systems of bacteria exist to

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Solution:

Restriction modification (R-M) systems of bacteria exist to protect bacteria from invading foreign DNA. This system is universal and is an important component of prokaryotic defense mechanisms against invading genomes. They occur in a wide variety of unicellular organisms, including eubacteria and archaea and comprise two contrasting enzymatic activities: a restriction endonuclease (REase) and a methyltransferase (MTase).