( ( A technique ) ( ( called ( ( ( polymerase ( chain reaction ) ) ( -LRB- ( PCR -RRB- ) ) ) ( is ( used ( to ( amplify ( ( ( a ( single copy ) ) ( of ( ( a ( small part ) ) ( of ( a ( gene ( many thousands ) ) ) ) ) ) ) ( of times ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN technique)) (VP (VBD called) (SBAR (S (NP (NP (NN polymerase) (NN chain) (NN reaction)) (PRN (-LRB- -LRB-) (NP (NNP PCR)) (-RRB- -RRB-))) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB amplify) (NP (NP (DT a) (JJ single) (NN copy)) (PP (IN of) (NP (NP (DT a) (JJ small) (NN part)) (PP (IN of) (NP (DT a) (NN gene) (QP (JJ many) (NNS thousands)))))) (PP (IN of) (NP (NNS times)))))))))))) (. .)))
A technique called polymerase chain reaction (PCR) is used to amplify a single copy of a small part of a gene many thousands of times.
(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))))))))) (. .)))