Topic: DNA Replication
As the DNA double helix is pulled apart by helicase, the parts of the DNA that are still twisted together become even more tightly wound, creating physical tension.
Steps:
Understanding the Question: What specific enzyme is responsible for preventing the DNA from "tangling" or getting too tight to open?
Key Formulas and Approach: Replication creates "torsional strain." An enzyme must cut, rotate, and reseal the DNA to fix this.
Detailed Solution:
Helicase unwinds the DNA, which causes **supercoiling** (over-twisting) further down the line.
Topoisomerase (specifically DNA Gyrase in bacteria) travels ahead of the replication fork.
It makes temporary cuts in the sugar-phosphate backbone, allows the DNA to swivel to release tension, and then glues it back together.
Without it, the DNA would become so tightly knotted that replication would stop.