Practice question

Heteroduplex DNA consists of strands originating from two different parental duplexes paired together. It forms when the Rad51-ssDNA presynaptic filament invades homologous duplex, opening the donor and annealing its complementary strand to the invading strand. This creates a D-loop structure where one donor strand is displaced. Branch migration can extend the heteroduplex region bidirectionally. If donor and recipient sequences differ at single nucleotides, mismatch in heteroduplex triggers mismatch repair, leading to gene conversion. Formation is central to recombination and mating-type switching.