We highlighted the differences in between the regulatory processes in prokaryotes and the more complex processes in eukaryotes, mainly the facts that in eukaryotes many transcription factors are needed to aid transcription and that DNA is many times condensed in heterochromatin, and therefore unavailable for RNA polymerase and other proteins.
Among some of the processes that affect gene expression we discussed histone acetylation, a mechanism through which heterochromatin is relaxed into euchromatin, making DNA available for DNA binding proteins, and methylation, a mechanism through which genes can be repressed or silenced, in some cases because it promotes de-acetylation of histones and DNA condensation into heterochromatin.
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