( ( In DNA ) ( , ( bonds ( ( ( ( form ( between ( bases ( on ( the ( two ( nucleotide chains ) ) ) ) ) ) ) and ) ( ( hold ( the chains ) ) together ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NNP DNA))) (, ,) (NP (NNS bonds)) (VP (VP (VBP form) (PP (IN between) (NP (NP (NNS bases)) (PP (IN on) (NP (DT the) (CD two) (JJ nucleotide) (NNS chains)))))) (CC and) (VP (VBP hold) (NP (DT the) (NNS chains)) (PRT (RP together)))) (. .)))
In DNA, bonds form between bases  on the two nucleotide chains and hold the chains together.
(ROOT (S (NP (NNP Dna)) (VP (VBZ consists) (PP (IN of) (NP (NP (CD two) (JJ long) (NNS chains)) (PP (IN of) (NP (NNS nucleotides)))))) (. .)))