why does "crossing over" involve non sister chromatids(homologues) instead of sister chromatids?
3 answers
One homologous chromosome is inherited from the organism's mother; the other from the organism's father.
A sister chromatid is a duplicate of itself and it occurs in mitosis. Homologous chromatids are one from each parent and this happens in meiosis.You can't cross over with yourself, crossing over aids in random assortment of the daughter cells or offspring.
It does not involve incest.
5 answers