Question

Ciprofloxacin inhibits dna gyrase, a bacterial topoisomerase that cuts dna ahead of the replication fork, winds the dna in a direction that relieves the twists added during dna synthesis, and then reseals the dna. in ciprofloxacin-treated bacteria, newly synthesized dna is found in fragments. based on this evidence, what activity of dna gyrase is likely to be inhibited by ciprofloxacin?

Answer 1

It inhibits the ligation activity.

Antimicrobial agents interfere with either DNA replication cell wall synthesis, plasma membrane integrity, ribosomal function, or folate synthesis. Ciprofloxacin belongs to fluoroquinolones class of antibiotics that interfere with DNA replication. DNA gyrase is a bacterial topoisomerase that cuts and then reseals DNA to change DNA topology during replication. The binding of ciprofloxacin to A subunit of gyrase enzyme stabilizing gyrase–DNA complex. This leads to inhibition the resealing (ligation) activity of the enzyme leaving the DNA fragmented. 

Answer 2

Answer:

Ciprofloxacin inhibits the action of DNA gyrase leading to those fragmented DNAs, which leads to ultimate death of the bacteria.

Explanation:

DNA gyrase is the enzyme which seals the fragments of the DNA.

During the DNA replication, DNA is produced in fragments due to the act of DNA polymerase on the DNA molecule. But as the DNA is produced, it leads to the formation of fragments. This needs to be sealed by the DNA gyrase which is needed to seal the fragments to form the whole circular DNA.

Ciprofloxacin inhibits the action of DNA gyrase leading to those fragmented DNAs, which leads to ultimate death of the bacteria.