Which organism type exhibits replication with DNA unwinding in multiple areas, occurs in the nucleus, and involves separation of sister chromatids during mitosis?

• A. Prokaryotic
• B. Eukaryotic
• C. Both
• D. Neither

Answer: (B)

The description points to cells that handle replication at multiple sites, keep DNA inside a nucleus, and separate identical sister chromatids during division. In eukaryotic cells, chromosomes are linear and numerous, so replication begins at many origins along the DNA, allowing unwinding at several places at once. The DNA is housed in the nucleus, where the mitotic machinery operates to organize and separate chromosomes. After DNA is replicated, the two sister chromatids stay joined at the centromere until mitosis, where they are finally pulled apart and distributed to the daughter cells. Prokaryotes, by contrast, have a single circular chromosome that typically replicates from one origin in the cytoplasm, lack a nucleus, and do not undergo mitosis with sister chromatid separation. So the organism type described is eukaryotic.