Why is fission of bacteria not considered mitosis

Mitosis is unnecessary because there is no nucleus or multiple chromosomes. This type of cell division is called binary fission. The cell division process of prokaryotes, called binary fission , is a less complicated and much quicker process than cell division in eukaryotes.

Because of the speed of bacterial cell division, populations of bacteria can grow very rapidly. The single, circular DNA chromosome of bacteria is not enclosed in a nucleus, but instead occupies a specific location, the nucleoid, within the cell. As in eukaryotes, the DNA of the nucleoid is associated with proteins that aid in packaging the molecule into a compact size. The packing proteins of bacteria are, however, related to some of the proteins involved in the chromosome compaction of eukaryotes.

The starting point of replication, the origin , is close to the binding site of the chromosome to the plasma membrane Figure 1. As the new double strands are formed, each origin point moves away from the cell-wall attachment toward opposite ends of the cell. As the cell elongates, the growing membrane aids in the transport of the chromosomes. After the chromosomes have cleared the midpoint of the elongated cell, cytoplasmic separation begins. A septum is formed between the nucleoids from the periphery toward the center of the cell.

When the new cell walls are in place, the daughter cells separate. Figure 1. Prokaryotic Cell Division. Binary Fission Binary fission is the method by which prokaryotes produce new individuals that are genetically identical to the parent organism. Learning Objectives Describe the process of binary fission in prokaryotes. The origin, or starting point of bacterial replication, is close to the binding site of the DNA to the plasma membrane.

Replication of the bacterial DNA is bidirectional, which means it moves away from the origin on both strands simultaneously. The formation of the FtsZ ring, a ring composed of repeating units of protein, triggers the accumulation of other proteins that work together to acquire and bring new membrane and cell wall materials to the site.

When new cell walls are in place, due to the formation of a septum, the daughter cells separate to form individual cells. Key Terms mitotic spindle : the apparatus that orchestrates the movement of DNA during mitosis karyokinesis : mitosis the first portion of mitotic phase where division of the cell nucleus takes place binary fission : the process whereby a cell divides asexually to produce two daughter cells.

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Do you want to LearnCast this session? This article has been posted to your Facebook page via Scitable LearnCast. Change LearnCast Settings. Scitable Chat. Register Sign In. Visual Browse Close. In both types of cells, DNA is copied and separated to form new cells in an organized manner. In both types of cells, cytoplasm is divided to form daughter cells via the process of cytokinesis. In both processes, if everything goes as planned, the daughter cells contain an exact copy of the parent cell's DNA.

In bacterial cells, the process is simpler, making fission faster than mitosis. Because a bacterial cell is a complete organism, fission is a form of reproduction. While there are some single-celled eukaryotic organisms, mitosis is most often used for growth and repair rather than reproduction. While errors in replication in fission are a way to introduce genetic diversity in prokaryotes, errors in mitosis can cause serious problems in eukaryotes e.

Mitosis includes a checkpoint to make certain both copies of DNA are identical. Eukaryotes use meiosis and sexual reproduction to ensure genetic diversity. While a bacterial cell lacks a nucleus, its genetic material is found within a special region of the cell called a nucleoid. Copying the round chromosome starts at a site called the origin of replication and moves in both directions, forming two replication sites. As the replication process progresses, the origins move apart and separate the chromosomes.

The cell lengthens or elongates. There are different forms of binary fission: The cell can divide across the transverse short axis, the longitudinal long axis, at a slant, or in another direction simple fission. Cytokinesis pulls the cytoplasm toward the chromosomes.

When replication is complete, a dividing line—called a septum—forms, physically separating the cytoplasm of the cells. A cell wall then forms along the septum and the cell pinches in two, forming the daughter cells.

While it's easy to generalize and say binary fission only occurs in prokaryotes, this isn't exactly true. Certain organelles in eukaryotic cells, such as mitochondria, also divide by fission. Some eukaryotic cells can divide via fission. For example, algae and Sporozoa may divide via multiple fission in which several copies of a cell are made simultaneously.

Mitosis is part of the cell cycle. The process is much more involved than fission, reflecting the complex nature of eukaryotic cells.

There are five phases: prophase, prometaphase, metaphase, anaphase, and telophase.