In: Biology
What is crossing over? How is meiosis related to this phenomenon?
Answer) Crossing over is also called as recombination sometimes, it is a process of exchange of chromosomal segments between non-sister chromatids of two homologous chromosomes. such process leads to the formation of a new combination of genes (on the exchanged segments) and gives rise to genetic diversity via gametes. this process occurs during Meiosis for the formation of gamete.
In the prophase I of meiosis I, duplicated chromosomes (a pair of homologous chromosomes) comes together in a process called as synapsis. it leads to chiasma formation, a point of crossing-over. at the chiasmata, non-sister chromatids of homologous chromosomes exchange their chromosomal segments. this process is called as Homologous crossing over of recombination ( see the image below; Synapsis and crossing over in Prophase I of meiosis I).