Q.(a) Which type of crossing over is mentioned in the above diagram ?
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Start your 14-day free trial to unlock the full solution →The figure depicts a single crossing over (one chiasma) between the linked genes A/a and B/b; it yields 2 parental and 2 recombinant chromatids, giving a recombination frequency of 50% for this event.
(a) During meiosis a bivalent is made of four chromatids, two from each homologous chromosome. In the diagram only the two inner non-sister chromatids come into contact and exchange segments at a single point (one chiasma) located between the A/a locus and the B/b locus. In the "after" panel each of these two chromatids shows exactly one junction where the shaded and hatched segments change over, which is the signature of a single crossing over. (A double crossing over would instead show two chiasmata, with each recombinant chromatid carrying two such junctions.)
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