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 nearly equal sized daughter cells. The genetic material is also equally partitioned, therefore, the daughter cells are genetically identical (unless a mutation occurs 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., Trypanosome), 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. Bacteria uses binary fission to reproduce quickly, thus allowing them to reproduce efficiently.
During binary fission, the DNA molecule divides and forms 2 DNA molecules. Each molecule moves towards the opposite side of the bacterium cell. At the same time, the cell membrane divides to form 2 daughter cells. In the process of division (in eukaryotes), first the division of nucleus (karyokinesis) takes place after which the division of cytoplasm (cytokinesis) takes place. After division, the new cells will grow and the process repeats itself.
For unicellular organism, cell division or fission leads to the creation of new individuals. Many different patterns of fission have been observed. Many bacteria and protozoa simply split into two equal halves during cell division. In organisms such as amoeba, The splitting of two cells during division can take place in any plane.