Final answer:
The electron micrographs of the 30-nm fiber support the zigzag model, indicating how nucleosomes are arranged alternately with linker DNA to enable DNA compaction within the nucleus.
Step-by-step explanation:
The electron micrographs of the 30-nm fiber support the zigzag model of chromatin structure. Electron micrographs show an alternation of nucleosomes positioned to the right and left, connected by straight segments of linker DNA. This pattern fits the zigzag model, which suggests that the 30-nm fiber is formed by a series of nucleosomes that are arranged in a zigzag pattern, with linker DNA between them. This model helps to explain how the structure of the chromatin fiber enables the compacting of eukaryotic DNA within the cell nucleus.