Perhaps they are making multiple contacts. Chromatin condenses the DNA and makes it unavailable for transcription. The DNA is wrapped tightly around the outside of a histone core, almost two turns, tightly bent, histone tails protruding outwards from the surface. One major role of activators is to remove the general repression conferred by nucleosomes. Conversely, some negative regulation favors it.
Cells have active control over the stability of chromatin.
In some cases, nucleosomes are precisely positioned, in part because the DNA sequence favors certain locations and in part as a result of specific regulatory events. Reduce positive charge of histones, giving weaker DNA binding b. Destabilize interactions between nucleosomes 3. It is important to understand these methods, and to be aware of the capabilities and limitations of each method. Here are some general principles, for your own information. I won't ask specifically about these on the exam.