( ( Our ( red ( blood cells ) ) ) ( ( ( ( ( lose ( their nucleus ) ) , ) so ) ( have ( ( no chromosomes ) ( at all ) ) ) ) . ) )
(ROOT (S (NP (PRP$ Our) (JJ red) (NN blood) (NNS cells)) (VP (VP (VBP lose) (NP (PRP$ their) (NN nucleus))) (, ,) (ADVP (RB so)) (VP (VBP have) (NP (NP (DT no) (NNS chromosomes)) (PP (IN at) (NP (DT all)))))) (. .)))
Our red blood cells lose their nucleus, so have no chromosomes at all.
(ROOT (S (NP (NP (DT The) (NNS cells)) (PP (IN of) (NP (DT all) (NNS protists)))) (VP (VBP have) (NP (DT a) (NN nucleus))) (. .)))