What is the difference between chiasma and crossing over?
1 Answer
Dec 13, 2017
Crossing over is a phenomenon that takes place between nonsister chromatids of homologous chromosomes and the phenomenon takes place at molecular level. Chiasma is a manifestation of that crossing over.
Explanation:
During first meiotic division of a cell, homologous chromosomes would pair up and at pachytene stage of prophase 1 crossing over takes place.
Crossing over is not seen under microscope. Chiasmata are seen under microscope in Diplotene and Diakinesis stages of prophase 1.
As the division progresses, the homologous chromosomes start to pull apart. At the point of exchange the homologues remain attached, as if by a knot. This point is called chiasmata.
Chiasmata gradually shift towards telomeres and mostly disappear in diakinesis.
