Practice question

In prokaryotes short-patch base excision repair gap filling after AP incision and dRP removal requires polymerase capable of single-nucleotide insertion and possessing 5'→3' exonuclease for nick translation. DNA Polymerase I encoded by polA fulfills roles: its polymerase domain inserts correct nucleotide using undamaged complementary strand as template, while 5'→3' exonuclease removes downstream 5' dRP or flap. DNA Pol III is major replicase unsuitable for repair synthesis, Pol II participates in SOS lesion bypass, and Pol β is eukaryotic counterpart of Pol I lacking in prokaryotes, highlighting Pol I's central repair function.