Binary fission is the process in which a single cell divides into two new cells, called "daughter" cells. The daughter cells produced by binary fission have exactly the same number of chromosomes as the original cell (also known as haploid cells). The amount of time it takes a bacteria to divide is called "doubling time," and this can vary from as short as 20 minutes to as long as days, depending on the bacteria.
Binary fission begins when the chromosomes (which contain DNA) in a single-cell organism start to divide in half and the cell begins to elongate. The next step involves the chromosomes completely separating from one another, and moving to opposite ends of the cell. A cross wall then develops in the middle of the cell and, in the final step of binary fission, the cell splits in half along the cross wall.
Binary fission is similar to the process of mitosis in multicellular, eukaryotic organisms; however, there are some importance differences. The most important one is that mitosis only makes new cells, not new organisms. Additionally, mitosis has an additional step at the beginning of its division, called prophase. During prophase, the nucleus that contains the cell's chromosomes dissolves and the chromosomes become visible. This step does not exist in binary fission because the organisms that undergo binary fission (eukaryotes) do not have a nucleus; the chromosomes are simply free floating in the cell.
While binary fission is a type of asexual reproduction for single-cell organisms, there are different types that some multicelled organisms go through. Fragmentation occurs when a part of an organism is separated from the main body and begins growing on its own; this is seen with different types of weeds and also potatoes. Parthenogenesis occurs when an organism develops from an unfertilized egg; this has been observed in different types of reptiles, as well as honeybees.