The chromosomes and genes contained within DNA are replicated during the S phase of the interphase cell cycle. DNA replication occurs within the nucleus of eukaryotes and in the cytoplasm of prokaryotes. DNA replication occurs in all living organisms.
In the nucleus of every cell are long strings of DNA. The DNA contains all the necessary information to make and control every cell in a living organism. DNA replication is a semiconservative process where the parental strand serves as the template for the new complementary daughter strands. There are proofreading mechanisms during replication to keep errors at a low frequency.