( Scientists ( ( think ( that ( ( cells ( of ( some ( protist colonies ) ) ) ) ( became ( specialized ( for ( different jobs ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Scientists)) (VP (VBP think) (SBAR (IN that) (S (NP (NP (NNS cells)) (PP (IN of) (NP (DT some) (JJ protist) (NNS colonies)))) (VP (VBD became) (NP (NP (JJ specialized)) (PP (IN for) (NP (JJ different) (NNS jobs)))))))) (. .)))
Scientists think that cells of some protist colonies became specialized for different jobs.
(ROOT (S (NP (NNS Scientists)) (VP (VBP think) (SBAR (S (NP (NNS protists)) (VP (VBP are) (NP (DT the) (JJS oldest) (NNS eukaryotes)))))) (. .)))