Bacteria in the digestive system are composed of only one cell. The bacteria are called prokaryotes. They reproduce by a type of asexual reproduction called binary fission. Binary fission means one cell splits into two cells. Because one cell creates another from its own DNA, they resulting cell is exactly identical to the first.
The DNA molecules inside the prokaryotes attaches to the plasma membrane and begins to replicate. Replication starts at a point on the parent chromosome and goes in both directions. The newly forming chromosome also attaches to the plasma membrane near the parent chromosome.
The cell stretches outward to twice its original size or larger. Growth of the cell between the two spots where each chromosome attached pulls the chromosomes apart. This is how the cell gets ready to become two cells. As the distance between chromosomes grows, the cell membrane begins to push between them.
The cell membrane grows between the parent chromosome and the new chromosome completely. This forms the cell wall. Once the cell wall is completely formed, the chromosomes are separated completely and two cells are formed.
Two Bacteria Cells
The parent cell and new cell are exactly the same. Each cell has the same DNA. Both cells can continue to replicate in this manner. At times, new DNA molecules will begin developing as in Step 2 before the two cells have completely split apart from each other.