In anaphase, sister chromatids separate and become full-fledged chromosomes that move to opposite poles. in anaphase, sister chromatids separate and become full-fledged chromosomes that move to opposite poles. in telophase chromosomes become less condensed and new nuclear envelopes form. in cytokinesis the cytoplasm divides. in telophase chromosomes become less condensed and new nuclear envelopes form. in cytokinesis the cytoplasm divides. most of the cell's life is spent in interphase, when growth occurs. cells that are about to divide replicate their dna. most of the cell's life is spent in interphase, when growth occurs. cells that are about to divide replicate their dna. in prophase microtubules form the mitotic spindle, and the nuclear envelope breaks up. in prophase microtubules form the mitotic spindle, and the nuclear envelope breaks up. at metaphase, the mitotic spindle is fully formed and chromosomes are lined up in the center of the cell. at metaphase, the mitotic spindle is fully formed and chromosomes are lined up in the center of the cell.