Cells employ two primary pathways to repair DSBs: homologous recombination (HR) and non-homologous end joining (NHEJ).
Homologous Recombination (HR): This error-free repair mechanism uses a sister chromatid as a template to accurately repair the break. HR is active primarily during the S and G2 phases of the cell cycle. Non-Homologous End Joining (NHEJ): This process directly ligates the broken DNA ends without the need for a homologous template. Although faster, NHEJ is more error-prone than HR and can lead to mutations. NHEJ operates throughout the cell cycle but is particularly active in the G1 phase.
