what are sister and non sister chromatids???????
Sister chromatids: Definition for sister chromatids is, Two identical strands joined by a common centromere as a result of a chromosome that duplicated during the S phase of the cell cycle. Sister chromatids are separated during mitosis so that the two daughter cells would have identical sets of chromosomes.
Non sister chromatids: Definition for non sister chromatids is, Either of the two chromatids of any of the paired (homologous) chromosomes. Non-sister (homologous) chromatids form chiasma(ta) to exchange genetic material during meiosis (i.e. Prophase I).