Related Experiment Video
Updated: Aug 8, 2026

Application of Laser Micro-irradiation for Examination of Single and Double Strand Break Repair in Mammalian Cells
Published on: September 5, 2017
Abnormal distribution of double strand breaks in DNA after direct action of ionizing energy
Abstract:
Experiments on purified DNA irradiated under circumstances which maximize direct absorption of ionizing energy in the DNA suggest that double strand breaks to the DNA helix are caused when energy depositions in spheres of comparable size to the diameter of the DNA helix exceed a threshold energy of between 70 and 100 eV. Evidence is also presented that shows that these events can lead to non-random patterns of double strand breakage within the molecule which are manifested as an excess of small fragments of DNA.
Related Concept Videos
Nucleotide Excision Repair
Nucleotide Excision Repair
Fixing Double-strand Breaks
Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Nucleotide Excision Repair
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Fixing Double-strand Breaks

