Question

Since the parental double helix must rotate 360° to unwind each gyre of the helix, during the semi-conservative replication of the bacterial chromosome, some kind of "swivel" must exist. What do geneticists now know that the required swivel is?

a. Negative Supercoiling coming un-coiled
b. A transient break produced by the action of topoisomerase
c. A transient break produced by the action of Ligase
d. A transient break produced by the action of helices

Answer 1

The required swivel for the semi-conservative replication of the bacterial chromosome is a transient break produced by the action of topoisomerase. Topoisomerases, specifically topoisomerase II or DNA gyrase, introduce transient breaks in the DNA strands to relax the supercoiled chromosome, allowing for unwinding and replication to occur.

Step-by-step explanation:

During the semi-conservative replication of the bacterial chromosome, the required swivel is a transient break produced by the action of topoisomerase. Topoisomerases are enzymes that change the shape and supercoiling of the chromosome. Specifically, topoisomerase II, also known as DNA gyrase, relaxes the supercoiled chromosome by introducing transient breaks in the DNA strands. This allows for the unwinding and separation of the DNA strands, which is necessary for replication to occur.