試題詳解

16. Bacterial cells protect their own DNA from restriction enzymes (endonucleases) by _____.
(A) using DNA ligase to seal the bacterial DNA into a closed circle
(B) adding methyl groups to adenines and cytosines
(C) adding histones to protect the double-stranded DNA
(D) forming "sticky ends" of bacterial DNA to prevent the enzyme (endonuclease) from attaching.
(E) mutation of their genomic sequences to encode alternative proteins.