 Although homologous recombination varies widely among different organisms and cell types , most forms involve the same basic steps . After a double @-@ strand break occurs , sections of DNA around the 5 ' ends of the break are cut away in a process called resection . In the strand invasion step that follows , an overhanging 3 ' end of the broken DNA molecule then " invades " a similar or identical DNA molecule that is not broken . After strand invasion , the further sequence of events may follow either of two main pathways discussed below ( see Models ) ; the DSBR ( double @-@ strand break repair ) pathway or the SDSA ( synthesis @-@ dependent strand annealing ) pathway . Homologous recombination that occurs during DNA repair tends to result in non @-@ crossover products , in effect restoring the damaged DNA molecule as it existed before the double @-@ strand break . 
