Practice question

Euchromatin defines genomic domains remaining decondensed throughout interphase, staining lightly with Giemsa, sensitive to DNase I and early replicating. Genome-wide mapping shows enrichment for protein-coding genes, CpG islands, H3K4 trimethylation at transcription start sites, H3K36 trimethylation in bodies and hyperacetylation. It occupies interior nucleoplasm away from lamina, unlike peripheral heterochromatin. Histone acetyltransferases and ATP remodelers maintain open conformation permitting transcription factor access, origin firing and repair. Consequently gene density high, repeat content low and condensation minimal compared to heterochromatic satellite domains.