( ( ( DNA 's ) ( secondary structure ) ) ( ( is ( predominantly ( determined ( by ( base-pairing ( of ( ( the ( two ( polynucleotide strands ) ) ) ( ( wrapped ( around ( each other ) ) ) ( to ( form ( a ( double helix ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP DNA) (POS 's)) (JJ secondary) (NN structure)) (VP (VBZ is) (ADJP (RB predominantly) (VBN determined) (PP (IN by) (NP (NP (NN base-pairing)) (PP (IN of) (NP (NP (DT the) (CD two) (JJ polynucleotide) (NNS strands)) (VP (VBN wrapped) (PP (IN around) (NP (DT each) (JJ other))) (S (VP (TO to) (VP (VB form) (NP (DT a) (JJ double) (NN helix)))))))))))) (. .)))
DNA's secondary structure is predominantly determined by base-pairing of the two polynucleotide strands wrapped around each other to form a double helix.
(ROOT (S (NP (DT The) (JJ double) (NN helix) (NN dna) (NN shape)) (VP (VBZ forms) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (CD two) (JJ nucleotide) (NNS chains)) (VP (VB wrap) (PRT (RP around)) (NP (DT the) (JJ same) (NNS axis)))))) (. .)))