Question

In which order do the necessary enzymes act to repair a thymine dimer by nucleotide excision repair?a) nuclease, dna polymerase, rna primaseb) helicase, dna polymerase, dna ligasec) dna ligase, nuclease, helicased) dna polymerase, rna polymerase, dna ligasee) nuclease, dna polymerase, dna liga?

Answer 1

Answer:

The correct answer is b) "helicase, dna polymerase, dna ligase".

Explanation:

The formation of thymine dimers is the most common DNA damage caused by the exposure of UV light. The cell have a repair system to address this damage called nucleotide excision repair. In this process, a helicase separates the double-stranded DNA forming a bubble in the site of damage. After the site of damage has been removed, a DNA polymerase replaces the missing fragment of DNA and a DNA ligase binds the two double-stranded DNA fragments that were previously separated.

Answer 2

The order for the necessary enzymes that act to repair a thymine dimer by nucleotide excision repair is Endonuclease, DNA polymerase I, DNA ligase. Thymine dimer repair may be done by two mechanisms; Photoreactivation repair, the pre enzyme activated by blue light breaks the dimer restoring the normal base pairing. The  other method is excision repair; where the uvr system excises the dimer, and the gap is filled in by the proof-reading activity of DNA polymerase I.