Division in prokaryotic cells
Binary fission is the process by which prokaryotic cells divide. It is different from mitosis because prokaryotes lack a nucleus, spindle fibres and membrane-bound organelles.
A typical prokaryotic cell has one main circular DNA molecule and may also contain smaller circular DNA molecules called plasmids.
- The main circular DNA molecule is replicated.
- The plasmids replicate.
- The DNA copies are distributed as the cell prepares to separate.
- The cytoplasm divides to produce two daughter cells.
Rapid reproduction
Under ideal conditions, some bacteria may divide approximately once every 20 minutes. A short generation time can allow a population to:
- establish itself rapidly in a new habitat
- increase sufficiently quickly to compete with other microorganisms
- pass through many generations in a short period, providing more opportunities for mutations and increased genetic variation, including variation relevant to antibiotic resistance
Exam Tip: Do not describe binary fission as mitosis. In a prokaryote, the circular DNA and plasmids replicate and the cytoplasm then divides; there is no nuclear division.