( ( Each molecule ) ( ( is ( composed ( of ( ( ( four ( polypeptide chains ) ) -- ) ( ( ( two ( identical ( heavy chains ) ) ) and ) ( two ( identical ( light chains ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT Each) (NN molecule)) (VP (VBZ is) (VP (VBN composed) (PP (IN of) (NP (NP (CD four) (JJ polypeptide) (NNS chains)) (: --) (NP (NP (CD two) (JJ identical) (JJ heavy) (NNS chains)) (CC and) (NP (CD two) (JJ identical) (NN light) (NNS chains))))))) (. .)))
Each molecule is composed of four polypeptide chains--two identical heavy chains and two identical light chains.
(ROOT (S (NP (NNP Insulin)) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (CD two) (JJ polypeptide) (NNS chains))))) (. .)))