Single-celled prokaryotes undergo cell division through a process distinct from that of eukaryotes, due primarily to their lack of a nucleus. Because prokaryotes are unicellular organisms, cell division is their means of asexual reproduction (reproduction that does not involve fusion of gametes, producing offspring genetically identical to the parent). Thus, when a prokaryotic cell divides, each new cell is a completely new organism. The process by which prokaryotic cells divide is called binary fission, a type of asexual reproduction. Binary fission is less complex than cell division in eukaryotic cells.
- Binary fission begins when the cell's DNA begins to replicate. DNA in prokaryotic cells does not form sister chromatids as in eukaryotic cell division. The place on a prokaryotic chromosome where DNA replication begins is called the origin of replication.
- Once a new strand of DNA has begun to form, two origins exist: the origin on the original strand and the origin on the new strand. As DNA replication continues, the origin on the new strand moves to the opposite end of the cell from the origin on the original strand and the cell elongates.
- When DNA replication is complete, each chromosome coils toward its origin, segregating the DNA in opposite ends of the elongated cell. The cell pinches off between the coils of DNA and cytokinesis occurs, separating the cells. The daughter cells are identical, separate organisms.