Binary fission

Binary fission, meaning "division in half", refers to a method of asexual reproduction. It is the most common form of reproduction in prokaryotes and occurs in some single-celled eukaryotes. After replicating its genetic material, the cell divides into two equal sized daughter cells. The genetic material is also equally partitioned, therefore, the daughter cells are genetically identical (unless a mutation occurred during replication) to each other and the parent cell. They then split into two. Transverse binary fission divides the cell across the short axis (e.g., most bacilli-shaped bacteria), longitudinal binary fission across the long axis (e.g., Trypanosoma), and random binary fission across no defined axis (e.g., Amoeba). Some biologists use this term for multi-cellular organisms that asexually reproduce by dividing into two (e.g., some star fish). This is also known as fragmentation. Spirogyra, a type of algae also reproduces by binary fission.

For better understand of binary fission refer to Trypanosma division

As one would expect, creating a functional human body with 10 fingers and 10 toes from a single cell is a highly coordinated process of cell differentiation. By comparison, the growth of a single rod-shaped bacterium and its division into two cells would be expected to be relatively simple. A bacterial cell elongates until it reaches a specific length, then proceeds to septate at the center, and there you have it—two daughter cells. Easy stuff, right? However, it turns out that the two daughter cells are not always the same. Cells of members of three large and anciently-diverged clades of bacteria (Actinobacteria, Alphaproteobacteria, and Planctomycetes) grow from a single pole and divide asymmetrically, producing two daughter cells that are not identical at birth. Of course, this is also the well-known lifestyle of budding yeasts.

What types of evolutionary advantages might result from creating two different daughter cells? InCaulobacter crescentus, a stalk formed at one of the poles attaches the cell to surfaces, whereas a flagellum is formed at the other pole, making that cell motile. Reproductive asymmetries may prove advantageous in removing damaged or old cellular machinery from the population. By segregating the “old” macromolecules into one daughter cell and forcing the other cell to generate new macromolecules, bacterial lineages may be able to persist under stress conditions. In these instances, polar growth creates a heterogeneous population which could increase the fitness of a microbial species in response to environmental stress. It makes sense, therefore, to look for growth at the poles in other species as well. The question arises: could polar growth also contribute to an antibiotic resistant phenotype?