Matching Pairs mitosis GUIDE 8Online version order the steps by lina berardinelli 1 what was a once a single nucleus is now two thick nuclei. a cell wall (membrane) develops down the center of the old cell separating them 2 when a cell is not undergoing mitosis, the chromosomes are scattered about the nucleus 3 when a cell is about to undergo mitosis, chromosomes become visible as they thicken 4 they now begin to move to the center of the cell 5 once the chromosomes are line up at the center of the cell they divide. After they divide, the chromosomes begin moving to opposite ends of the cell 3 5 4 2 1