During which phase does DNA replication occur?

During which phase does DNA replication occur?

• A. DNA is replicated.
• B. DNA is created anew from proteins.
• C. Cytokinesis occurs.
• D. Chromosome condensation occurs.

Answer: (A)

DNA replication happens during the S phase of interphase, the part of the cell cycle when the genome is duplicated in preparation for division. The statement that DNA is replicated fits this timing perfectly because it describes the exact event occurring to copy the entire genome so both daughter cells can inherit a complete set of genetic material. This process is semi-conservative, meaning each new DNA molecule contains one old strand and one newly synthesized strand, ensuring fidelity of the copy. The other options don’t fit the timing or the process. DNA being created anew from proteins would violate how genetic information is stored and copied, since DNA replication uses existing DNA as a template rather than assembling DNA from proteins. Cytokinesis is the final splitting of the cytoplasm after mitosis, not a phase where DNA is duplicated. Chromosome condensation occurs during early mitosis (prophase) to compact the chromosomes, not during DNA replication.

DNA replication happens during the S phase of interphase, the part of the cell cycle when the genome is duplicated in preparation for division. The statement that DNA is replicated fits this timing perfectly because it describes the exact event occurring to copy the entire genome so both daughter cells can inherit a complete set of genetic material. This process is semi-conservative, meaning each new DNA molecule contains one old strand and one newly synthesized strand, ensuring fidelity of the copy.

The other options don’t fit the timing or the process. DNA being created anew from proteins would violate how genetic information is stored and copied, since DNA replication uses existing DNA as a template rather than assembling DNA from proteins. Cytokinesis is the final splitting of the cytoplasm after mitosis, not a phase where DNA is duplicated. Chromosome condensation occurs during early mitosis (prophase) to compact the chromosomes, not during DNA replication.