[Campbell Biology P.372] If a cell were unable to synthesize functional topoisomerase, what ... | Practice Question

If a cell were unable to synthesize functional topoisomerase, what immediate problem would arise during DNA replication?

  • A: The parental DNA strands would immediately re-pair after unwinding.
  • B: Increased twisting and strain ahead of the replication fork would halt unwinding.
  • C: RNA primers would not be synthesized, preventing DNA polymerase from initiating synthesis.
  • D: Daughter strands would be significantly shorter than parental strands.

Explanation

The text states: 'The untwisting of the double helix causes tighter twisting and strain ahead of the replication fork. Topoisomerase is an enzyme that helps relieve this strain by breaking, swiveling, and rejoining DNA strands.' Without functional topoisomerase, this strain would build up, making further unwinding by helicase difficult or impossible, effectively halting replication.