Question

The topoisomerase DNA gyrase will introduce negative supercoils into DNA. What effect will this enzyme have on relaxed, covalently closed DNA? A The DNA will become more susceptible to cutting by an exonuclease like DNAase I (B) The DNA will become overwound C) The treated DNA will migrate farther in an agarose gel than the relaxed DNA. D) Nucleotides will be removed from the circular DNA. E) The relaxed DNA will migrate farther in an agarose gel than the treated DNA.

Answer 1

The complementary strands of DNA double helix aare separated by two enzymes-- DNA gyrase and

DNA helicase.

This is called unwinding of a double stranded DNA.

DNA gyrase is a Type II of Topoisomerase which creats a double stranded break, requires ATP, and relieves positive and negative supercoils. It has the unique property of being able to introduce negative supercoils into relaxed circular DNA . Introducing these negative supercoils into circular DNA facilitates future replication because these introduced negative supercoils counteract the positive supercoils created when the double helix is opened for replication. So, the correct answer should be option [C] The treated DNA will migrate farther in an agarose gel than the relaxed DNA.