( ( ( ( ( ( Sex-linked genes ) ( are ( located ( on ( a ( sex chromosome ) ) ) ) ) ) , ) and ) ( ( X - ) ( linked ( genes ( are ( located ( on ( the ( X chromosome ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (JJ Sex-linked) (NNS genes)) (VP (VBP are) (VP (VBN located) (PP (IN on) (NP (DT a) (NN sex) (NN chromosome)))))) (, ,) (CC and) (S (NP (NNP X) (NNP -)) (VP (VBD linked) (SBAR (S (NP (NNS genes)) (VP (VBP are) (VP (VBN located) (PP (IN on) (NP (DT the) (NNP X) (NN chromosome))))))))) (. .)))
Sex-linked genes are located on a sex chromosome,  and X- linked genes are located on the X chromosome.
(ROOT (S (NP (JJ Sex-linked) (NNS traits)) (VP (VBP are) (VP (VBN located) (PP (IN on) (NP (NP (NNS genes)) (PP (IN on) (NP (NN sex) (NNS chromosomes))))))) (. .)))