To insert the insulin gene into bacterial DNA, both the bacterial plasmid and the human chromosome containing the insulin gene are treated with the same restriction enzyme. Using the same restriction enzyme ensures that
(a) DNA ligase is able to join the segments of human and bacterial DNA
(b) the exact length of nucleotides matching the insulin gene is removed from the plasmid
(c) both the bacterial and human DNA will contain sticky ends
(d) sticky ends in the cut plasmid and insulin gene are complementary.
Answer (d) : Each particular restriction enzyme produces unique sticky ends. Using the same enzyme for both the bacterial and human DNA will produce complementary sticky ends that can bind together by complementary base pairing. This would allow the human insulin gene to be inserted into the plasmid.
