Q. Why is it significant for chromosomes to be condensed during mitosis and decondensed during interphase?
During mitosis the major problem to be solved is the correct separation of chromosome sets between daughter cells. If chromosomes were decondensed long tiny fibers of the DNA would be dispersed in cytoplasm after the karyotheca breaking and chromosomes could not be easily pulled and organized by the spindle fibers.
During interphase the function of chromosomes that is of DNA molecules, is the synthesis of the RNA and thus of proteins. For this task it is necessary for functional molecular regions to be decondensed these regions form the euchromatin. During interphase in addition DNA replication occurs as a preparatory step for cell division. In this procedure it is fundamental for the exposition of the DNA molecules to serve as templates to new DNA chains under production.