( ( ( Protein Structure ) ( When ( ( amino ( acids bind ) ) ( together ( , ( they ( form ( a ( long chain ) ) ) ) ) ) ) ) ) ( ( called ( a polypeptide ) ) . ) )
(ROOT (S (NP (NP (NNP Protein) (NNP Structure)) (SBAR (WHADVP (WRB When)) (S (NP (JJ amino) (JJ acids) (NN bind)) (ADVP (RB together)) (, ,) (NP (PRP they)) (VP (VBP form) (NP (DT a) (JJ long) (NN chain)))))) (VP (VBD called) (NP (DT a) (NN polypeptide))) (. .)))
Protein Structure     When amino acids bind together, they form a long chain called a polypeptide.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN protein)) (VP (VBZ is) (VP (VBN formed) (SBAR (WHADVP (WRB when)) (S (NP (JJ amino) (NNS acids)) (VP (VBP are) (VP (VBN linked) (ADVP (RB together)) (PP (IN in) (NP (DT a) (JJ long) (NN chain))))))))) (. .)))