 After the stages of resection , strand invasion and DNA synthesis , the DSBR and SDSA pathways become distinct . The DSBR pathway is unique in that the second 3 ' overhang ( which was not involved in strand invasion ) also forms a Holliday junction with the homologous chromosome . The double Holliday junctions are then converted into recombination products by nicking endonucleases , a type of restriction endonuclease which cuts only one DNA strand . The DSBR pathway commonly results in crossover , though it can sometimes result in non @-@ crossover products ; the ability of a broken DNA molecule to collect sequences from separated donor loci was shown in mitotic budding yeast using plasmids or endonuclease induction of chromosomal events . Because of this tendency for chromosomal crossover , the DSBR pathway is a likely model of how crossover homologous recombination occurs during meiosis . 
