When does replication occur in DNA?

DNA replication occurs during the S phase of interphase, which is part of the cell cycle. Interphase consists of three stages: G1 (growth), S (synthesis), and G2 (growth). The S phase is dedicated to DNA replication, where the entire genome is duplicated to ensure that each daughter cell receives an identical copy of the genetic material. DNA replication occurs before the cell enters mitosis (or meiosis), the phase in which cell division takes place. Without replication during the S phase, the resulting daughter cells would not receive a full set of chromosomes, which would be detrimental to the organism.