Fig. 6.

A molecular model of interphase and mitotic chromatin. (A) Interphase chromatin is loosely packed, with many megacomplexes and pockets. Blue, purple, and dark blue, nucleosome-like particles, with heterogeneity denoted by the variability in colors; large gold bodies, megacomplexes. Megacomplexes (preribosomes, spliceosomes, transcription-preinitiation complexes, etc.) are interspersed between the nucleosome-like particles and macromolecular-complex–free pockets. (B) During mitotic chromosome condensation, most nucleosome-like particles form large clusters, thereby excluding or inhibiting the assembly of megacomplexes. Furthermore, chromatin dynamics (magnitude proportional to the size and number of the curved lines) also decrease. In both interphase and mitotic chromatin, ordered motifs are largely absent.