The third edition of chromatin structure and function brings the reader up to date with the remarkable progress in chromatin research over the past three years it has been extensively rewritten to cover new material on chromatin remodeling histone modification nuclear compartmentalization dna methylation and transcriptional co activators and co repressors. The third edition of chromatin structure and function brings the reader up to date with the remarkable progress in chromatin research over the past three years it has been extensively rewritten to cover new material on chromatin remodeling histone modification nuclear compartmentalization dna methylation. Chromatin is a mass of genetic material composed of dna and proteins that condense to form chromosomes during eukaryotic cell division chromatin is located in the nucleus of our cells the primary function of chromatin is to compress the dna into a compact unit that will be less voluminous and can fit within the nucleus. The structure and function of chromatin chromatin is a complex of macromolecules composed of dna rna and protein which is found inside the nucleus of eukaryotic cells chromatin exists in two forms heterochromatin condensed and euchromatin extended