Bacterial Replication and Cell Division
Before a bacterium divides, it must copy its entire genome and distribute one complete copy to each daughter cell. Bacterial DNA replication begins at a single origin and proceeds in both directions, while the cell grows and then divides by binary fission, with chromosome copying, segregation, and the formation of a division septum coordinated so that each new cell inherits a full genome.
Definition
Bacterial replication and cell division is the coordinated process by which a bacterium duplicates its chromosome from a defined origin and partitions the copies into two daughter cells through binary fission.
Scope
This topic covers the bacterial cell cycle: initiation and progression of DNA replication, the replisome, segregation of the duplicated chromosome, and cytokinesis by binary fission, including the assembly of the division machinery. It is a mechanistic reference overview and does not provide clinical instructions.
Core questions
- How and where does bacterial DNA replication begin, and how does it proceed around the chromosome?
- What molecular machine carries out replication, and how is its accuracy ensured?
- How are the duplicated chromosomes segregated to opposite ends of the cell?
- How is the timing of division coordinated with completion of replication?
Key concepts
- Origin of replication (oriC)
- Bidirectional, semiconservative replication
- Replisome and DNA polymerase III
- Leading and lagging strand synthesis
- Replication fork and terminus
- Chromosome segregation
- Binary fission and septum formation
- Z-ring and the divisome
Mechanisms
Bacterial replication is semiconservative and bidirectional: it initiates at a single defined origin, where the chromosome is unwound, and two replication forks proceed in opposite directions until they meet at the terminus. The replisome, organized around the replicative DNA polymerase, copies the leading strand continuously and the lagging strand discontinuously, with proofreading and mismatch repair ensuring high fidelity, as reviewed by O'Donnell and colleagues. As replication proceeds, the two daughter chromosomes are actively organized and segregated toward opposite cell poles, a process Wang and colleagues describe in terms of chromosome organization and partitioning machinery. Division then occurs by binary fission, in which the cell assembles a contractile ring at midcell that directs synthesis of a septum and physically separates the two daughter cells, each having received a complete genome.
Clinical relevance
Several antibacterial drug targets lie in the replication and division machinery, and the rate of replication and division contributes to how quickly bacterial populations grow and respond to stress. This entry describes the underlying biology and is not a guide to drug selection or patient management.
History
The semiconservative nature of DNA replication and the enzymology of DNA polymerases established the molecular basis of genome copying, and bacteria such as Escherichia coli served as the central experimental model. Subsequent work on the replisome and on chromosome segregation and the division apparatus, synthesized in reviews by O'Donnell and by Wang and colleagues, integrated replication with the bacterial cell cycle.
Key figures
- Arthur Kornberg
- Mike O'Donnell
- David Rudner
Related topics
Seminal works
- odonnell-2013
- wang-2013
Frequently asked questions
- What does it mean that bacterial replication is bidirectional?
- Replication starts at one origin and two replication forks move away from it in opposite directions around the circular chromosome until they meet at the terminus, so the whole genome is copied in roughly half the time a single fork would take.
- How do bacteria divide?
- Most bacteria divide by binary fission: after the chromosome is copied and segregated, a ring-shaped division machine assembles at midcell and builds a septum that splits the cell into two daughter cells.