Nucleosomes with deacetylated and acetylated histones
After summarizing the main points of gene regulation in prokaryotes we started discussing mechanisms used by eukaryotic organisms.
We are building upon what we already know about gene regulation in prokaryotes and highlighting the added complexity found in eukaryotes. Some of the reasons for which additional or more complex mechanisms are required in eukaryotes are:
- DNA is found in a nucleus
- DNA is wrapped around histones
- Nucleosomes can be condensed in heterochromatin
- In multicellular eukaryotes different genes are expressed in different cell types or at different stages of development
We started explaining how a cell solves the problem of accessing DNA that is highly condensed (heterochromatin). Acetylation of histones, specifically of lysine residues, holds the key. We described how histone acetyl transferases (HATs), and histone deacetylases (HDs) add and remove acetyl groups from lysine residues in histones.
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