Single strand DNA repair

- Specific endonucleases release the oligonucleotides containing damages bases.- DNA polymerase and ligase fill and reseal the gap.- Repairs bulky helix-distorting lesions, thymidine dimers.- Occurs in G₁ phase of cell cycle.

Defective in xeroderma pigmentosum (inability to repair DNA pyrimidine dimers caused by UV exposure.- Findings: dry skin, extreme light sensitivity, skin cancer.