( ( ( ( ( ( The cell ) ( ( membrane forms ) ( around ( each nucleus ) ) ) ) and ) then ) ( ( the ( two cells ) ) ( split apart ) ) ) . )
(ROOT (S (S (NP (DT The) (NN cell)) (VP (VBD membrane) (NP (NNS forms)) (PP (IN around) (NP (DT each) (NN nucleus))))) (CC and) (RB then) (S (NP (DT the) (CD two) (NNS cells)) (VP (VBD split) (ADVP (RB apart)))) (. .)))
The cell membrane forms around each nucleus and then the two cells split apart.
(ROOT (S (NP (CD Two) (NNS membranes)) (VP (VBP form) (NP (NP (DT the) (NN mitochondrion) (NN structure)) (PP (IN of) (NP (DT a) (NN cell))))) (. .)))