試題詳解

20. A 400-bp covalently closed circular DNA with a linking number of 35 has 5 negative supercoils. When the linking number of this DNA is changed to 38 by a topoisomerase, this DNA will have
(A) 3 positive supercoils.
(B) 3 negative supercoils.
(C) 2 positive supercoil.
(D) 2 negative supercoils.
(E) relaxed.