( Crossing-over ( ( is ( ( the breaking ) ( of ( ( ( one maternal ) and ) ( ( one ( paternal chromosome ) ) ( resulting ( in ( ( the exchange ) ( of ( ( corresponding sections ) ( of ( DNA ( between ( nonsister chromatids ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Crossing-over)) (VP (VBZ is) (NP (NP (DT the) (NN breaking)) (PP (IN of) (NP (NP (CD one) (NN maternal)) (CC and) (NP (NP (CD one) (JJ paternal) (NN chromosome)) (VP (VBG resulting) (PP (IN in) (NP (NP (DT the) (NN exchange)) (PP (IN of) (NP (NP (JJ corresponding) (NNS sections)) (PP (IN of) (NP (NP (NNP DNA)) (PP (IN between) (NP (NN nonsister) (NNS chromatids))))))))))))))) (. .)))
Crossing-over is the breaking of one maternal and one paternal chromosome resulting in the exchange of corresponding sections of DNA between nonsister chromatids.
(ROOT (S (NP (NP (NNP Exchange)) (PP (IN of) (NP (NN dna) (NNS segments)))) (VP (VBZ happens) (PP (IN between) (NP (NP (JJ non-sister) (NNS chromatids)) (PP (IN of) (NP (NP (RB homologous) (NNS chromosomes)) (PP (IN during) (NP (NN crossing-over)))))))) (. .)))