Which phase of the cell cycle is characterized by DNA replication?

Which phase of the cell cycle is characterized by DNA replication?

• A. G1 phase
• B. G2 phase
• C. S phase
• D. M phase

Answer: (C)

DNA replication happens during the S phase, the synthesis phase of the cell cycle. In this stage, the cell duplicates its genetic material so each daughter cell will inherit a complete copy. The double helix is unwound, and new nucleotides are added to each template strand by DNA polymerase in the 5' to 3' direction, creating semi-conservative replication with sister chromatids held together at the centromere. This doubling of DNA content occurs before division, while the chromosome count remains the same until mitosis. Other phases focus on growth (G1), final preparation and quality checks (G2), or actual division (M phase), but DNA replication occurs specifically in the S phase.

DNA replication happens during the S phase, the synthesis phase of the cell cycle. In this stage, the cell duplicates its genetic material so each daughter cell will inherit a complete copy. The double helix is unwound, and new nucleotides are added to each template strand by DNA polymerase in the 5' to 3' direction, creating semi-conservative replication with sister chromatids held together at the centromere. This doubling of DNA content occurs before division, while the chromosome count remains the same until mitosis. Other phases focus on growth (G1), final preparation and quality checks (G2), or actual division (M phase), but DNA replication occurs specifically in the S phase.