In which order do the necessary enzymes act to repair a thymine dimer by nucleotide excision repair?
A)nuclease,DNA polymerase,RNA primase
B)helicase,DNA polymerase,DNA ligase
C)DNA ligase,nuclease,helicase
D)nuclease,DNA polymerase,DNA ligase

Question

Quizplus · Accepted Answer

In nucleotide excision repair, the damaged section of DNA is first recognized and excised by a nuclease enzyme. Then, a DNA polymerase fills in the gap by adding new nucleotides, using the intact strand as a template. Finally, DNA ligase seals the nick to complete the repair. Therefore, the correct order of enzyme action is nuclease, DNA polymerase, and DNA ligase. Choice B is incorrect because helicase is not involved in nucleotide excision repair, and RNA primase is not needed because RNA is not involved in DNA repair. Choice C is also incorrect because DNA ligase acts last in the repair process, after the gap has been filled in by DNA polymerase.

In Which Order Do the Necessary Enzymes Act to Repair