Final answer:
In nucleotide excision repair, damaged DNA is excised by enzymes such as UvrABC endonuclease followed by synthesis of new DNA by DNA polymerase, and the final sealing of the strand by DNA ligase.
Step-by-step explanation:
Nucleotide Excision Repair Enzymes
In nucleotide excision repair (NER), damaged DNA is excised by a series of enzymes and proteins. This repair mechanism is tasked with removing bulky lesions such as pyrimidine dimers that result from UV exposure. Notably, two enzymes, UvrABC endonuclease and DNA polymerase (DNA pol), play crucial roles in this pathway. UvrABC endonuclease recognizes the distortion in DNA's double helix and makes cuts on both sides of the damaged area, allowing the removal of the damaged strand. Subsequently, DNA polymerase synthesizes new DNA to fill in the gap, using the intact strand as a template. Once synthesis is complete, the strand is sealed back together with a phosphodiester linkage catalyzed by DNA ligase, restoring the DNA to its correct sequence.