Binary fission

Most Archaea and Bacteria cells accumulate biomass until a critical volume is reached when they seperated into two identical daughter cells. This division occurs in a single plane of symmetry. To some extent division dictates the simplicity in cell shape and the prevalence of cell numbers of 2n when cells appear in clusters or chains. The procedure of cell division is outlined in Figure 1 and can be divided into four steps that are

(1)Growth and replication

(2) FtsK ring construction and chromosome separation

(3) FtsK ring constriction and septation

(4) and lastly cell separation.

The procedure is poorly understood involving several proteins and an extremely efficient control system. A middle role is played by FtsK a functional and structural analog of the eukaryotic tubulins. The FtsK was named after the filamentous temperature-sensitive mutants which were first recognized in E. coli. At some 

                                                            Figure 1:  Bacterial cell division

temperatures mutants were unable to septate and became long multinucleate filaments a phenomenon seen in some wild-type lactobacilli and  in Streptomyces.During the procedure of chromosomal replication FtsK monomers start to move to a point midway among the two ends of the cell. It is unclear how this happens but inhibitors have been identified at the poles preventing the initiation of unwanted separation. The FtsK proteins form  a ring and  it is certain that at this point other proteins are recruited to the  locality  to deal  with  the  site-specific recombination events which must take  place  to allow  the  separation of the  two  replicated chromosomes. The formation of a septum starts with constriction of the FtsK ring across the width of the cell and the septum forms completely so in which the daughter cell becomes separate in Figure 1. There  are  undoubtedly several other mechanisms governing the  act of cell division since  the  entire contents of the cell membrane, cell including, proteins,  ribosomes, lip- ids , cell wall and  any extra-chromosomal material must also be divided among the  two cells as both daughter cells are immediately and  fully functional. It is remarkable which this process is repeated every 40 minutes through E. coli. The universality of FtsK-like proteins across both the Archaea and Bacteria suggests in which this is an evolutionarily conserved fundamental mechanism for single-celled life.