These come with challenges, such as, the ability when some genes need to be expressed and when some do not. Know the differences between gene expression in prokaryotes and eukaryotes. (hat) histone intertwine and form condensed dna. The default state of dna is off(condensed) You turn it on by decondensing it. Histone: is heavily positively charged, lots of lysine. The whole thing becomes a net positive- it goes toward the more negative charge. The histone as a more negative charge and replaces the backbone. For a prokaryote the default states is always on for eukaryotes the default state in off . Dna is more tightly oacked and must open for the rna polymerase to access the genes and start transcription. Iclicker question: the sequence that are used to regulate the chromation condensation process are probably nucleotides in the dna. Generic enzyme- there are always sections avalible to transcribe therefore the dna is not completely off : splicing.