Final answer:
The statement that both the nucleosome and solenoid fibers are correct components of eukaryotic nuclear DNA packaging is true. The nucleosome fiber has a diameter of 11 nm, while the solenoid fiber has a 30 nm diameter, and both contribute to the hierarchical structure of DNA compaction in eukaryotic cells.
Step-by-step explanation:
The correct answer to the question 'Which of the following statements about eukaryotic nuclear DNA packaging is true?' is c) Both A and B. The nucleosome fiber has a diameter of 11 nm and represents the initial level of DNA compaction in eukaryotic cells, with DNA wrapped around histone proteins to form a structure resembling 'beads on a string'. Additionally, this nucleosome fiber is further compacted into a structure called the solenoid fiber, which has a diameter of 30 nm. This solenoid fiber forms when nucleosomes are arranged in a helical or spiral fashion, making the DNA more compact and allowing for its efficient packaging within the eukaryotic nucleus.
Eukaryotic cells must pack their DNA efficiently to fit the long molecules into the relatively small volume of the nucleus. They do this through a hierarchical structure that goes from DNA wrapped around histones (nucleosomes), to a 30 nm fiber, and eventually to even higher-order structures that form chromosomes during cell division. Comparatively, prokaryotic organisms like bacteria do not have a nucleus and instead have their DNA packaged in a different manner, such as the coiled loop domains found in E. coli, which are associated with Hu proteins and other non-histone proteins.