Final answer:
The nucleosomes' three-dimensional reproducible configuration represents the tertiary structure, which is part of the organizational hierarchy of DNA that also includes primary, secondary, and quaternary structures, though the latter refers to protein organization rather than DNA.
Step-by-step explanation:
The correct answer to the given question regarding the structure of nucleosomes is tertiary structure. The levels of structural organization for DNA within the cell begin with the primary structure, which is the sequence of nucleotides in the DNA strand itself. The secondary structure involves the winding of DNA around histone proteins to form nucleosomes, which resemble beads on a string under an electron microscope. Tertiary structures are formed when these nucleosomes assume a reproducible configuration in three-dimensional space as higher-order packing occurs, controlling access to DNA regions. This complex arrangement facilitates further compaction and the regulation of gene expression. The quaternary structure, while relevant in the context of protein organization, is not applicable to the organization of nucleosomes. Additionally, the organization of structures from least to most complex goes from DNA, nucleosome, chromatin, to chromosome.
To clarify the association of these structures with protein organization, the primary structure of a protein refers to its amino acid sequence, the secondary structure to the basic helices or sheets formed, the tertiary structure is the overall three-dimensional shape of a single protein molecule, and the quaternary structure concerns the arrangement of multiple protein subunits.