Final answer:
The 30nm fiber is compacted further by the binding of non-histone proteins, leading to a tightly packed chromatin structure.
Step-by-step explanation:
The 30nm fiber is further compacted through the association of specific non-histone proteins. These non-histone proteins cause the nucleosomes to fold over on themselves to form a tightly packed structure. Unlike histone acetylation, which results in the loose packing of nucleosomes and increased access to DNA, the binding of non-histone proteins provides additional structural support for higher-order chromatin organization, leading to more compact chromatin that is essential for cell division and the maintenance of chromosomal integrity in the nucleus.