Practice question

Eukaryotic meiotic recombination visible as chiasmata formation occurs during prophase I after homologous chromosomes synapse. Substage leptotene condenses chromosomes, zygotene initiates synaptonemal complex assembly pairing homologs, pachytene maintains full synapsis allowing recombination nodules to mature. Spo11 introduces programmed double-strand breaks early, resection produces single-stranded overhangs that invade homologous duplex via RAD51 and DMC1 recombinases during pachytene. Resolution of double Holliday junctions at this stage produces reciprocal crossovers essential for accurate disjunction and genetic diversity. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.