( ( The ( cell wall ) ) ( ( is ( ( a ( critical structure ) ) ( in ( bacterial cells ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN cell) (NN wall)) (VP (VBZ is) (NP (NP (DT a) (JJ critical) (NN structure)) (PP (IN in) (NP (JJ bacterial) (NNS cells))))) (. .)))
The cell wall is a critical structure in bacterial cells.
(ROOT (S (NP (DT A) (NN cell) (NN wall)) (VP (VBZ is) (RB not) (ADJP (JJ present) (PP (IN in) (NP (NN animal) (NNS cells))))) (. .)))