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Chromatin is the form of DNA present when a cell is not dividing.
When a cell undergoes division the chromatin coils up to form a chromosome.
Chromatin is a complex of DNA and protein. The proteins include histones, which form into complexes of eight proteins. The DNA is coiled round these histone octamers to form nucleosomes, the basic structure of chromatin. The nucleosomes are then arranged into higher order structures allowing greater packaging of the DNA.
Dividing cells have condensed chromatin as sseebeck correctly states but the DNA is still wrapped round the histones. It is interesting that the histones can be chhemically modified by enzymes involved in gene regulation. Certain post-translational modifications of histones allow a more open structure so that RNA polymerases can access the genes and transcribe them. So in short most of the DNA is packed away and can't be transcribed but some expressed genes have a more open structure. The histones nucleosomes can be moved or removed from the DNA in active genes.