Final answer:
The core complex consists of two sets of histone proteins H2A, H2B, H3, and H4, forming a nucleosome, which when wrapped by DNA, further compacts to form a 30 nm fiber structure.
Step-by-step explanation:
The core complex mentioned in the question refers to a grouping of histone proteins around which DNA wraps to form a nucleosome, a fundamental unit of chromatin structure. Specifically, this core consists of two sets of four types of histone proteins: H2A, H2B, H3, and H4, with two molecules of each making up an octameric core. When DNA wraps around this histone core, it creates a "bead-like" structure known as a nucleosome. Linker DNA then connects these nucleosomes, resembling "beads on a string." The nucleosomes can further coil into a 30 nm fiber, increasing the compaction of chromatin within the cell nucleus.