( ( To ( uncover ( ( the mechanism ) ( of ( calcium transport ) ) ) ) ) ( , ( Hilgemann ( ( had ( to ( control ( ( the movement ) ( of ( molecules ( across ( the ( cell membrane ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (S (VP (TO To) (VP (VB uncover) (NP (NP (DT the) (NN mechanism)) (PP (IN of) (NP (NN calcium) (NN transport))))))) (, ,) (NP (NNP Hilgemann)) (VP (VBD had) (S (VP (TO to) (VP (VB control) (NP (NP (DT the) (NN movement)) (PP (IN of) (NP (NP (NNS molecules)) (PP (IN across) (NP (DT the) (NN cell) (NN membrane)))))))))) (. .)))
To uncover the mechanism of calcium transport, Hilgemann had to control the movement of molecules across the cell membrane.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT the) (NN movement)) (PP (IN of) (NP (NP (NNS molecules)) (PP (IN across) (NP (DT a) (ADJP (JJ membrane) (PP (IN without) (NP (NP (DT the) (NN input)) (PP (IN of) (NP (NN energy)))))) (JJ passive) (NN transport))))))) (. .)))