( ( ( Plant cells ) ( have ( a ( cell wall ) ) ) ) ( , ( ( animal cells ) ( ( do not ) . ) ) ) )
(ROOT (S (S (NP (NNP Plant) (NNS cells)) (VP (VBP have) (NP (DT a) (NN cell) (NN wall)))) (, ,) (NP (NN animal) (NNS cells)) (VP (VBP do) (RB not)) (. .)))
Plant cells have a cell wall, animal cells do not.
(ROOT (S (NP (DT A) (NN cell) (NN wall)) (VP (VBZ is) (VP (VBN found) (PP (PP (IN in) (NP (DT a) (NN plant) (NN cell))) (CONJP (CC but) (RB not)) (PP (IN in) (NP (DT an) (NN animal) (NN cell)))))) (. .)))
A cell wall is found in a plant cell but not in an animal cell.