Methylases add methyl groups to the new DNA, at the same positions as the original strands. Now the two daughter helices are indistinguishable from each other, and from the original helix. Bacterial cell fission, in which the circular chromosome is replicated. Eukaryotic cell cycle , including Mitosis, in which multiple linear chromosomes are separated and passed on. Bacterial cell fission Replication of the chromosome starts at the origin attached to the cell wall, near the midpoint of the cell.
Replication occurs bidirectionally around the chromosome, as the cell elongates.
In eukaryotes, DNA replication actually occurs in S phase of interphase. The big problem with eukaryotes is that they have to replicate linear chromosomes with special ends called telomeres. To do this, they need to use a special enzyme called telomerase, actually related to the reverse transcriptase of HIV virus. For more information on telomerase, go here .