During the pachytene stage of prophase I, the phenomenon of crossing over occurs. Which enzyme complex is primarily responsible for mediating this recombination event?

Solution

1. Crossing over involves the physical breakage and reunion of DNA strands between non-sister chromatids.
2. This process requires the coordinated action of enzymes to cut and rejoin DNA molecules.
3. The enzyme complex responsible for this site-specific recombination is known as recombinase.
4. While ligase is involved in sealing the nicks, the primary mediator of the recombination event is recombinase.
5. Hence the answer is (B).