( ( The ( polymerase ( chain reaction ) ) ) ( ( makes ( ( many copies ) ( of ( ( ( a gene ) or ) ( other ( DNA segment ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN polymerase) (NN chain) (NN reaction)) (VP (VBZ makes) (NP (NP (JJ many) (NNS copies)) (PP (IN of) (NP (NP (DT a) (NN gene)) (CC or) (NP (JJ other) (NN DNA) (NN segment)))))) (. .)))
The  polymerase chain reaction makes many copies of a gene or other DNA segment.
(ROOT (S (NP (DT The) (NN polymerase) (NN chain) (NN reaction)) (VP (VBZ is) (NP (NP (DT a) (NN way)) (PP (IN of) (S (VP (VBG making) (NP (NP (NNS copies)) (PP (IN of) (NP (DT a) (NN gene))))))))) (. .)))