( It ( is ( represented ( by ( the ( uppercase ( letter R. ) ) ) ) ) ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (VP (VBN represented) (PP (IN by) (NP (DT the) (NN uppercase) (NN letter) (NNP R.)))))))
It is represented by the uppercase letter R.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (VP (VBD represented) (PP (IN by) (NP (DT a) (JJ single) (NN letter)))))) (, ,) (NP (JJ dominant) (NNS alleles)) (VP (VBP are) (VP (VBN represented) (PP (IN by) (NP (JJ uppercase) (NNS letters))))) (. .)))