A bacterium inherits a mutation that renders its topoisomerase enzyme nonfunctional. What phenotype would you expect to see in this bacterium?
A)The cell would accumulate broken DNA because overwinding cannot be corrected, so the cell would be unable to replicate and would die.
B)The cell would accumulate supercoiled DNA, but otherwise it would be perfectly normal.
C)The cell would accumulate relaxed DNA, which would make DNA replication and cell division highly disorganized and lead to cell death.
D)The cell would accumulate relaxed DNA, but otherwise it would be perfectly normal.
E)The cell would be unaffected because bacteria have many different topoisomerases that are involved in replication.

Question

Quizplus · Accepted Answer

Topoisomerases are enzymes that help to relieve the torsional strain that builds up in DNA as it is being replicated, transcribed, and repaired. If a bacterium inherits a mutation that renders its topoisomerase enzyme nonfunctional, it would be unable to correct overwinding of its DNA. This would result in the accumulation of broken DNA, which would make it impossible for the cell to replicate and eventually lead to cell death.

A Bacterium Inherits a Mutation That Renders Its Topoisomerase Enzyme