( ( ( Crossing over ) ( ( the process ) ( ( in which ) ( ( segments ( of ( chromatide ( of ( homologous chromosomes ) ) ) ) ) ( are ( exchanged ( as they ) ) ) ) ) ) ) ( ( synapse ( during meiosis ) ) . ) )
(ROOT (S (S (VP (VBG Crossing) (PRT (RP over)) (NP (NP (DT the) (NN process)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (NP (NNS segments)) (PP (IN of) (NP (NP (NN chromatide)) (PP (IN of) (NP (JJ homologous) (NNS chromosomes)))))) (VP (VBP are) (VP (VBN exchanged) (PP (IN as) (NP (PRP they)))))))))) (VP (VBP synapse) (PP (IN during) (NP (NNS meiosis)))) (. .)))
Crossing over the process in which segments of chromatide of homologous chromosomes are exchanged as they synapse during meiosis.
(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)))))))) (. .)))