INTERPHASE Most of the cell cycle (about 90%) Cell metabolizes and performs its function inside the organism Cell doubles everything in its cytoplasm –Increases the amount of protein inside the cell –increases the number of organelles –grows in size Chromosomes in the form of chromatin

Steps in Interphase G1 –G = gap –Organelles double, cells grow in size… S –S = synthesis (DNA synthesis) –Most important event is chromosome replication (occurs in nucleus) G2 –Final preparation before division

PROPHASE Early Prophase –Chromosomes coil and condense to become visible –Nucleoli disappears –Sister chromatids present and held together by the centromere –Spindle begins to form Late Prophase –Nuclear envelope breaks down –Spindle attaches to the centromeres and moves the chromosomes toward the center of the cell

METAPHASE Spindle is completely formed The centromeres on the chromosomes are lined up on an imaginary equator between the poles The spindle is attached to each sister chromatid and this helps to keep the chromosomes in the center of the cell

ANAPHASE The sister chromatids are separated and now each is considered a daughter chromosome Motor proteins found on the centromeres move the chromosomes toward the opposite poles of the cell Spindle microtubules attached to chromosomes shorten Spindle microtubules that are not attached to chromosomes lengthen to elongate the cell and force the poles further apart in preparation for daughter cells