What part of interphase does DNA replicate?

DNA replication occurs during the S phase (Synthesis phase) of interphase. Interphase is the longest phase in the cell cycle and consists of three stages: G1 (gap 1), S (synthesis), and G2 (gap 2). During the S phase, the cell actively synthesizes a copy of its DNA. Prior to this phase, in the G1 phase, the cell undergoes growth and prepares for the energy-intensive process of DNA replication. The S phase is the critical time during which the entire genome is replicated. This ensures that each daughter cell will have an identical copy of the genetic material when the cell divides in mitosis or meiosis.