What is the primary purpose of the process known as nucleotide excision repair?

Nucleotide excision repair is primarily focused on repairing bulky DNA lesions, particularly those caused by exposure to ultraviolet (UV) light, such as thymidine dimers. These dimers occur when two adjacent thymine bases bond together due to UV radiation, distorting the DNA structure and hindering replication and transcription. The nucleotide excision repair mechanism identifies and excises a short segment of the damaged DNA strand around the dimer, allowing the DNA polymerase to fill in the gap with the correct nucleotides and DNA ligase to seal the newly synthesized segment back into the DNA strand.

The significance of this repair mechanism is underscored by its role in maintaining genomic stability, as failure to correct such lesions can lead to mutations, cell cycle arrest, or even cancer. Therefore, the ability to effectively repair thymidine dimers is crucial in protecting cells from the detrimental effects of DNA damage caused by environmental factors.