( ( Only ( eukaryotic cells ) ) ( ( have ( a nucleus ) ) . ) )
(ROOT (S (NP (RB Only) (JJ eukaryotic) (NNS cells)) (VP (VBP have) (NP (DT a) (NN nucleus))) (. .)))
Only eukaryotic cells have a nucleus.
(ROOT (S (NP (NP (DT The) (NNS cells)) (PP (IN of) (NP (DT all) (NNS protists)))) (VP (VBP have) (NP (DT a) (NN nucleus))) (. .)))