what happens during crossing over

Crossing over is a process that occurs during meiosis when chromosomes of the same type are lined up. During crossing over, parts of the chromosome can be switched between two chromosomes - one from the mother and one from the father - that contain the same genes but may have different forms of the genes. This exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis results in new allelic combinations in the gametes. Crossing over increases the variability of a population and prevents the accumulation of deleterious combinations of alleles, while also allowing some parental combinations to be passed on to the offspring. This way, there is a balance between maintaining potentially useful allelic combinations as well as providing the opportunity for variation and change. In summary, crossing over is a process that increases genetic diversity by exchanging genetic material between homologous chromosomes during meiosis.