( ( Crossing over ) ( ( ( involves ( ( the exchange ) ( of ( ( chromosome segments ) ( between ( non-sister chromatids ) ) ) ) ) ) ( during ( ( the production ) ( of gametes ) ) ) ) . ) )
(ROOT (S (S (VP (VBG Crossing) (PRT (RP over)))) (VP (VBZ involves) (NP (NP (DT the) (NN exchange)) (PP (IN of) (NP (NP (NN chromosome) (NNS segments)) (PP (IN between) (NP (JJ non-sister) (NNS chromatids)))))) (PP (IN during) (NP (NP (DT the) (NN production)) (PP (IN of) (NP (NNS gametes)))))) (. .)))
Crossing over involves the exchange of chromosome segments between non-sister chromatids during the production of gametes.
(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)))))))) (. .)))