DNAkaksoiskierrekatkaisua

DNAkaksoiskierrekatkaisu, often referred to as DNA double-strand break (DSB) in English, is a critical type of DNA damage that occurs when both strands of the DNA double helix are severed. This damage can arise from various sources, including ionizing radiation, certain chemicals, and reactive oxygen species. DSBs are considered one of the most severe forms of DNA damage because they pose a significant threat to genomic integrity. If not repaired accurately, they can lead to chromosomal rearrangements, mutations, and ultimately cell death.

Cells have evolved sophisticated repair mechanisms to deal with DNA double-strand breaks. The two major pathways are non-homologous end joining (NHEJ) and homologous recombination (HR). NHEJ is a faster but more error-prone pathway that directly ligates the broken DNA ends, often resulting in small insertions or deletions. HR, on the other hand, is a more accurate pathway that uses a homologous DNA template, typically the sister chromatid, to repair the break without loss of genetic information. The choice between these pathways is influenced by the cell cycle stage and the availability of a template. The proper functioning of these repair pathways is essential for maintaining genome stability and preventing diseases like cancer.