<P> There is evidence that, in some species, sister chromatids are the preferred template for DNA repair . Sister chromatid cohesion is essential for the correct distribution of genetic information between daughter cells and the repair of damaged chromosomes . Defects in this process may lead to aneuploidy and cancer, especially when checkpoints fail to detect DNA damage or when incorrectly attached mitotic spindles don't function properly . </P> <P> Mitotic recombination is primarily a result of DNA repair processes responding to spontaneous or induced damages . (Also reviewed in Bernstein and Bernstein, pp 220--221). Homologous recombinational repair during mitosis is largely limited to interaction between nearby sister chromatids that are present in a cell subsequent to DNA replication but prior to cell division . Due to the special nearby relationship they share, sister chromatids are not only preferred over distant homologous chromatids as substrates for recominational repair, but have the capacity to repair more DNA damage than do homologs . </P> <P> Studies with the budding yeast Saccharomyces cerevisiae indicate that inter-sister recombination occurs frequently during meiosis, and up to one - third of all recombination events occur between sister chromatids . </P>

How are the chromosome copies separated from each other