Problem:
Patient with Xeroderma pigmentosum experience increased frequency of skin cancer. This is due to a defect in the nucleotide excision repair (NER) pathway. This pathway involves the removal of UV damaged nucleotides with nucleases and the removed sequence is then filled in by DNA polymerase. Compare/contrast this process with DNA proofreading.
a) they are likely to occur in difference phases of the cell cycle
b) only one involves the breaking of phosphodiester bonds
c) if the nuclease activity is from DNA polymerase, one is likely to involve 5' to 3' nuclease activity while the other involves the 3' to 5' activity
d) one likely involves an exonuclease while the other an endonuclease
Please select correct answer and also provide explaination.