( ( The nucleus ) ( ( is ( bounded ( by ( ( a ( double membrane ) ) ( called ( the ( nuclear envelope ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN nucleus)) (VP (VBZ is) (VP (VBN bounded) (PP (IN by) (NP (NP (DT a) (JJ double) (NN membrane)) (VP (VBN called) (NP (DT the) (JJ nuclear) (NN envelope))))))) (. .)))
The nucleus is bounded by a double membrane called the nuclear envelope.
(ROOT (S (NP (NNP Nuclear) (NNP enevelope)) (VP (VBZ is) (NP (NP (DT a) (JJ double) (NN membrane)) (PP (IN of) (NP (NP (DT the) (NN nucleus)) (SBAR (WHNP (WDT that)) (S (VP (VBZ encloses) (NP (DT the) (JJ genetic) (NN material))))))))) (. .)))