Question

In the uvr excision repair system in E. coli, which enzyme routinely synthesizes DNA to replace the excised strand?

A. DNA polymerase III

B. RNA polymerase II

C. DNA polymerase V

D. DNA polymerase I

Answer 1

In the UVR excision repair system in E. coli, DNA polymerase I (option D) is the enzyme that synthesizes DNA to replace the excised strand, particularly during nucleotide excision repair to fix thymine dimers and other lesions.

Step-by-step explanation:

In the UV excision repair system in E. coli, the enzyme responsible for synthesizing DNA to replace the excised strand is DNA polymerase I. It removes the RNA nucleotides that were previously inserted as a primer and fills in the gap with DNA nucleotides. In nucleotide excision repair, which is important for correcting damage such as thymine dimers caused by UV light, the damaged DNA is removed by a cut at both ends of the lesion, and the correct nucleotides are replaced with the help of DNA polymerase I.



Afterward, the remaining gap is sealed with a phosphodiester linkage by DNA ligase. Among the choices given: A. DNA polymerase III, B. RNA polymerase II, C. DNA polymerase V, and D. DNA polymerase I, the correct answer is D.