The video above shows the process by which bacterial cells reproduce themselves. Looks simple, doesn't it? It's only a colony of cells elongating before splitting in two. Don't be fooled -- appearances can be deceiving. As is so common throughout biology, the apparent simplicity at the macro level masks remarkable complexity at the micro or molecular level.
In eukaryotes, cell division occurs by either meiosis (sex cells) or mitosis (somatic cells). Bacteria, however, undergo neither of those processes (they are asexual and contain no membrane-enclosed organelles or nuclei). Bacterial cell division occurs by a process known as binary fission. Rod-shaped bacteria (e.g. Escherichia coli or Salmonella typhimurium) elongate to twice their original length. This is followed by invagination of the cell membrane, and the formation of a septal ring in the middle (Vicente et al., 2006; Weiss, 2004). The elongated bacterial cell splits down the middle, forming two daughter cells. Some bacteria exhibit variations on this mechanism. For example, in Caulobacter, no septum is formed (Poindexter and Hagenzieker, 1981) and its division is asymmetrical (Judd et al., 2003)