( ( An operon ) ( ( is ( ( ( a region ) ( of DNA ) ) ( that ( consists ( of ( ( ( ( one or ) more ) genes ) ( that ( encode ( ( the proteins ) ( needed ( for ( a ( specific function ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (NN operon)) (VP (VBZ is) (NP (NP (DT a) (NN region)) (PP (IN of) (NP (NNP DNA))) (SBAR (WHNP (WDT that)) (S (VP (VBZ consists) (PP (IN of) (NP (NP (QP (CD one) (CC or) (JJR more)) (NNS genes)) (SBAR (WHNP (WDT that)) (S (VP (VBP encode) (SBAR (S (NP (DT the) (NNS proteins)) (VP (VBD needed) (PP (IN for) (NP (DT a) (JJ specific) (NN function)))))))))))))))) (. .)))
An operon is a region of DNA that  consists of one or more genes that encode the proteins needed for a specific function.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN operon)) (VP (VBZ consists) (PP (IN of) (NP (NP (QP (CD one) (CC or) (JJR more)) (NNS genes)) (SBAR (WHNP (WDT that)) (S (VP (VBP encode) (SBAR (S (NP (DT the) (NNS proteins)) (VP (VBD needed) (PP (IN for) (NP (DT a) (JJ specific) (NN function)))))))))))) (. .)))