( Sarcomeres ( ( are ( ( the ( smallest ( contractile unit ) ) ) ( of ( cardiac muscle ) ) ) ) . ) )
(ROOT (S (NP (NNS Sarcomeres)) (VP (VBP are) (NP (NP (DT the) (JJS smallest) (NN contractile) (NN unit)) (PP (IN of) (NP (JJ cardiac) (NN muscle))))) (. .)))
Sarcomeres are the smallest contractile unit of cardiac muscle.
(ROOT (S (NP (DT A) (NN sarcomere)) (VP (VBZ is) (NP (NP (DT the) (JJS smallest) (NN contractile) (NN portion)) (PP (IN of) (NP (DT a) (NN muscle))))) (. .)))