In which phase of the cell cycle does DNA replication occur?

In which phase of the cell cycle does DNA replication occur?

• A. G2 phase
• B. M phase
• C. S-phase of interphase
• D. G1 phase

Answer: (C)

DNA replication occurs during the S phase of interphase. In this phase, the cell duplicates its entire genome so that each chromosome becomes two sister chromatids held together at the centromere. This preparation ensures that, when the cell eventually divides in mitosis, each daughter cell receives an identical set of genetic information. Earlier in the cycle, during G1, the cell grows and carries out normal functions; after replication, the cell enters G2 to complete preparation for division and to check for errors. M phase is the actual division process (mitosis and cytokinesis), not DNA replication.

DNA replication occurs during the S phase of interphase. In this phase, the cell duplicates its entire genome so that each chromosome becomes two sister chromatids held together at the centromere. This preparation ensures that, when the cell eventually divides in mitosis, each daughter cell receives an identical set of genetic information. Earlier in the cycle, during G1, the cell grows and carries out normal functions; after replication, the cell enters G2 to complete preparation for division and to check for errors. M phase is the actual division process (mitosis and cytokinesis), not DNA replication.