In eukaryotic cells, where does DNA replication primarily occur?

• A. In the nucleus during S phase of interphase
• B. In the nucleolus during prophase of mitosis
• C. In the cytoplasm on free ribosomes
• D. In the Golgi apparatus during G1 phase

Answer: (A)

Verified step by step guidance

1. Understand that DNA replication is the process by which a cell duplicates its DNA before cell division.
2. Recall that in eukaryotic cells, DNA is contained within the nucleus, and replication must occur where the DNA is located.
3. Identify the phase of the cell cycle when DNA replication takes place, which is the S phase (Synthesis phase) of interphase.
4. Recognize that other options such as the nucleolus, cytoplasm, or Golgi apparatus are not the primary sites of DNA replication.
5. Conclude that DNA replication primarily occurs in the nucleus during the S phase of interphase.