Whatn functions do restriction enzymes have in living cells?

Answer 1

In the living bacterial cell, these enzymes destroy the DNA of certain invading viruses (bacteriophages), thus placing a "restriction" on the number of viral strains that can cause infection; the bacterium's own DNA is protected from cleavage by methyl (-CH3) groups, which are added by enzymes at the recognition sites to mask them.

Answer 2

Restriction enzymes function in living cells to act as a defense mechanism against foreign DNA, such as viral or bacterial DNA. They recognize specific DNA sequences and cleave the DNA at these sites, protecting the cell from potential harm by degrading the foreign genetic material. Additionally, restriction enzymes are also used in genetic engineering techniques, such as molecular cloning.