 Homologous recombination via the SDSA pathway occurs in cells that divide through mitosis and meiosis and results in non @-@ crossover products . In this model , the invading 3 ' strand is extended along the recipient DNA duplex by a DNA polymerase , and is released as the Holliday junction between the donor and recipient DNA molecules slides in a process called branch migration . The newly synthesized 3 ' end of the invading strand is then able to anneal to the other 3 ' overhang in the damaged chromosome through complementary base pairing . After the strands anneal , a small flap of DNA can sometimes remain . Any such flaps are removed , and the SDSA pathway finishes with the resealing , also known as ligation , of any remaining single @-@ stranded gaps . 
