Replication Transcription and Translation --- This video provides amazing animations of the aforementioned processes although the audio is pretty rough the animations alone make it worth it. Skip through the first minute or so to get to the good stuff!
DNA packed into chromatin - histone and nonhistone proteins; repeating unit is nucleosome - DNA wrapped around core of 8 histones. Chromatin maintains structure. Acetylation of histones occurs at ends - plays key role, controlled by histone acetyl transferse (HAT and HDAC). Must become physically accessible/uncoiled for translation - HDAC results in tight coiling. In some cancer cells, an overrecruiment of HDAC resulting in hyper-acetylation and closed chromatin structure.
Why are people in industrialized countries obese? Both mice and people have a gene called agouti. If it is turned on in a mouse, the mouse turns yellow and is obese and prone to diabetes and cancer. When pregnant yellow agouti mothers were fed BPA ( which we get from water bottles and tin cans) more yellow, unhealthy babies were born than normal... [Excellent Article on Epigenetics and Diet]