( ( ( ( ( DNA ( encodes ( ( ( proteins and ) proteins ) ( are ( needed ( to ( make DNA ) ) ) ) ) ) ) , ) so ) ( ( ( each type ) ( of ( organic molecule ) ) ) ( needs ( ( the other ) ( for ( its ( own existence ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP DNA)) (VP (VBZ encodes) (SBAR (S (NP (NNS proteins) (CC and) (NNS proteins)) (VP (VBP are) (VP (VBN needed) (S (VP (TO to) (VP (VB make) (NP (NN DNA))))))))))) (, ,) (IN so) (S (NP (NP (DT each) (NN type)) (PP (IN of) (NP (JJ organic) (NN molecule)))) (VP (VBZ needs) (NP (NP (DT the) (JJ other)) (PP (IN for) (NP (PRP$ its) (JJ own) (NN existence)))))) (. .)))
DNA  encodes proteins and proteins are needed to make DNA, so each type of organic molecule needs the other  for its own existence.
(ROOT (S (NP (NNP Dna)) (VP (VBZ encodes) (NP (NP (NNS instructions)) (PP (IN for) (NP (NNS proteins) (NNS molecules))))) (. .)))