Final answer:
One H1 protein is associated with each solenoidal turn of chromatin, helping to stabilize the condensed structure of the 30 nm fiber in the cell nucleus.
Step-by-step explanation:
The process of DNA packing involves condensation through several orders to fit into the small confines of a cell nucleus. The fundamental unit of this compaction is the nucleosome, which consists of DNA wrapped around a core of eight histone proteins. When DNA is packaged into a 30 nm chromatin fiber, known as a solenoid, these nucleosomes are arranged in a helical structure that is stabilized by the binding of another histone protein called H1. There is one H1 protein per nucleosomal unit in this solenoid structure, which corresponds to about one to two turns of the nucleosome helix. In summary, there is one H1 protein per solenoidal turn of chromatin.