( They ( ( are ( ( ( ( ( ( the ( cell membrane ) ) , ) ( the cytoplasm ) ) , ) and ) ( the cytoskeleton ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP are) (NP (NP (DT the) (NN cell) (NN membrane)) (, ,) (NP (DT the) (NN cytoplasm)) (, ,) (CC and) (NP (DT the) (NN cytoskeleton)))) (. .)))
They are the cell membrane , the cytoplasm , and the cytoskeleton .
(ROOT (S (NP (DT The) (NN cytoskeleton)) (VP (VBZ is) (NP (NP (DT the) (NN skeleton)) (PP (IN of) (NP (DT the) (NN cell))))) (. .)))