During the cell cycle, which phase is when DNA replication occurs?

During the cell cycle, which phase is when DNA replication occurs?

• A. G1
• B. S
• C. G2
• D. M

Answer: (B)

DNA replication happens during the synthesis phase. This part of the cycle is dedicated to copying the cell’s genetic material so each daughter cell will receive a complete set of chromosomes. During this phase, each chromosome is duplicated to form two sister chromatids held together at the centromere, doubling the cell’s DNA content in preparation for division. The preceding phase is focused on growth and metabolism, and the following phase is a preparation and checkpoint stage before division; the division itself occurs later in the process. So the synthesis phase is the window when DNA is actually copied.

DNA replication happens during the synthesis phase. This part of the cycle is dedicated to copying the cell’s genetic material so each daughter cell will receive a complete set of chromosomes. During this phase, each chromosome is duplicated to form two sister chromatids held together at the centromere, doubling the cell’s DNA content in preparation for division. The preceding phase is focused on growth and metabolism, and the following phase is a preparation and checkpoint stage before division; the division itself occurs later in the process. So the synthesis phase is the window when DNA is actually copied.