Figure 1.

Genome organization and function. A: The human genome is hierarchically organized to maintain function. Individual chromosomes, which are segregated into chromosome territories, are composed of a number of sub-compartments, loops and nucleosomes. B: Gene and chromosome position is related to activity. In general, gene dense chromosomes are more internal and gene-poor chromosomes are more peripheral within the nucleus. Also, inactive genes are frequently observed within the interior of their host chromosome. Upon activation, genes relocate to the periphery of the chromosome or looped out into the interchromatin space, where they are exposed to high local concentrations of transcriptional machinery and various nuclear bodies.