Final answer:
DNA replication takes place in the nucleus of eukaryotic cells, whereas the nucleolus is responsible for synthesizing the components of ribosomes.
Step-by-step explanation:
DNA replication always occurs in the nucleus of eukaryotic cells. This process involves unwinding the double helix, copying its genetic information, and generating two identical DNA molecules. In contrast, the components of ribosomes, specifically ribosomal RNA (rRNA), are synthesized in the nucleolus, a distinct region within the nucleus. The nucleolus aggregates rRNA with associated proteins to assemble ribosomal subunits, which are subsequently transported to the cytoplasm where ribosomes are formed. Ribosomes are not involved in DNA replication; instead, they are the sites where proteins are synthesized.