Binary fission is a form of asexual reproduction in which a single prokaryotic cell splits into two genetically identical daughter cells by duplicating its genome and partitioning cellular contents.
Process and regulation
In bacteria and archaea, binary fission begins with replication of the circular chromosome from a single origin of replication. Newly synthesized daughter chromosomes are actively segregated toward opposite poles by partitioning systems such as ParA/ParB in some species. Concurrently, the cell elongates and builds a division apparatus known as the divisome. A key component is FtsZ, a tubulin‑like protein that assembles into a ring at the future division site and recruits other proteins to form a contractile ring. The divisome directs synthesis of new peptidoglycan and membrane to form a septum that gradually constricts the cell. Regulatory proteins, including the MinCDE system in Escherichia coli, ensure that septation occurs at mid‑cell to produce equal daughter cells and prevent division over unsegregated nucleoids (nucleoid occlusion). Once constriction is complete and daughter chromosomes are separated, cell wall remodeling enzymes split the septum, yielding two discrete cells. The entire cycle can be completed in minutes under optimal conditions, enabling rapid population doubling.
Examples and significance
Binary fission is the predominant reproductive strategy of bacteria and most archaea, from rod‑shaped Bacillus and Escherichia coli to cocci like Streptococcus and halophilic archaea. Some species exhibit variations on this theme: budding yeast‑like division in Planctomycetes, snapping division in Corynebacterium, or multiple fission in some cyanobacteria. Organelles of eukaryotic cells such as mitochondria and chloroplasts also replicate by binary fission, reflecting their bacterial ancestry. Because binary fission produces genetically identical offspring, populations expand rapidly and maintain clonal integrity unless mutations or horizontal gene transfer introduce variation. Many antibiotics, including β‑lactams and FtsZ inhibitors, target processes essential for binary fission, making the division machinery a key focus of antimicrobial research and biotechnology.
Binary fission underlies the growth and reproduction of prokaryotes, providing a simple but highly regulated mechanism for genome duplication and cell division.
Related Terms: Cell division, FtsZ, Septum, Asexual reproduction, Mitosis