When does DNA replication occur?

When does DNA replication occur?

• A. Before cellular division (mitosis or meiosis)
• B. During cytokinesis
• C. After cellular division
• D. During protein synthesis

Answer: (A)

The essential idea is that a cell must copy its entire DNA before it splits so both new cells get a full set of genetic information. In eukaryotic cells this replication happens in the S phase of the cell cycle, with enzymes like DNA polymerase building new strands using the old ones as templates. This creates two identical copies that will be separated when the cell undergoes mitosis or meiosis, ensuring each daughter cell receives a complete genome. It isn’t happening during cytokinesis, which is just the final splitting of the cell’s cytoplasm, nor during protein synthesis, which uses DNA’s information to make proteins rather than copying the DNA itself. If replication occurred after division, the daughter cells wouldn’t have a complete genome to pass on.

The essential idea is that a cell must copy its entire DNA before it splits so both new cells get a full set of genetic information. In eukaryotic cells this replication happens in the S phase of the cell cycle, with enzymes like DNA polymerase building new strands using the old ones as templates. This creates two identical copies that will be separated when the cell undergoes mitosis or meiosis, ensuring each daughter cell receives a complete genome. It isn’t happening during cytokinesis, which is just the final splitting of the cell’s cytoplasm, nor during protein synthesis, which uses DNA’s information to make proteins rather than copying the DNA itself. If replication occurred after division, the daughter cells wouldn’t have a complete genome to pass on.