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Binary fission, mitosis and meiosis are the main forms of cell division. Binary fission and mitosis are forms of asexual reproduction, in which the mother cell divides to form two identical daughter cells. Meiosis, on the other hand, is a form of sexual reproduction in which a cell divides and distributes its genetic material between the two daughter cells.
The main difference between binary fission and mitosis
While both binary fission and mitosis are forms of cell division that duplicate cells, binary fission is the predominant form of reproduction of prokaryotic organisms , while mitosis occurs in eukaryotic cells , such as plant cells. and those of animals.
Another difference between both forms of cell division is that in binary fission the dividing cells lack a nucleus , while in mitosis the dividing cell has a nucleus . To better understand the processes, let’s look at some of the characteristics of prokaryotic and eukaryotic cells.
prokaryotic and eukaryotic cells
- Prokaryotic organisms are simple cells that lack a nucleus (a structure that houses the cell’s genetic material) and organelles (integrated structures in the cytoplasm that have different functions, depending on the type of cell). Your DNA (deoxyribonucleic acid) consists of one or two circular chromosomes .
- Eukaryotic cells , by contrast, are complex cells that have a nucleus and organelles , and their DNA is made up of multiple linear chromosomes.
In both types of cells the DNA is replicated and separated to form new cells, and the cytoplasm is divided in the process of reproduction to form daughter cells through cytokinesis or cytokinesis. In both processes, if they go smoothly, the daughter cells contain an exact copy of the mother cell’s DNA.
In bacterial cells, the cell division process is simpler, which makes binary fission faster than mitosis. Because a bacterial cell is itself an independent organism, binary fission is a form of reproduction . While there are some single-celled eukaryotic organisms, mitosis is predominantly a tissue growth and repair mechanism, rather than a reproductive mechanism of the organism.
While errors in DNA replication in binary fission are one way to introduce genetic diversity into prokaryotic organisms, errors in mitosis can cause serious problems in organisms with eukaryotic cells; for example, they can cause cancer. Mitosis includes a control mechanism of DNA replication to ensure that both copies are identical. The genetic diversification of eukaryotic organisms is generated through meiosis, the generation of gametes in sexual reproduction.
The process of binary fission
Although a bacterial cell lacks a nucleus, its genetic material is found within a special area of the cell called the nucleoid. The copy of the chromosomes, which are circular in shape, begin at a certain site in the cell called the origin of replication and evolve in opposite directions, generating two replication sites. As the replication process progresses, these replication sites separate, which in turn separates the chromosomes. The cell then elongates and takes on an oval shape.
There are different forms of binary fission. The cell can be divided along its transverse axis (the shortest axis of its oval shape; see figure above), along its longitudinal axis (the longest axis), taking a certain inclination with respect to the axes, or in another direction (simple fission). Cytokinesis moves the cytoplasm toward the chromosomes.
When replication is complete, a dividing plane called a septum is formed , which physically separates the cytoplasm of the new cells, as shown in the upper figure. A cell wall then forms along the septum, and the mother cell collapses in the area of the new cell wall, forming daughter cells.
It is not possible to generalize and affirm that binary fission only occurs in prokaryotic organisms. Certain organelles in eukaryotic cells, such as mitochondria, also divide by binary fission. Also some eukaryotic cells divide by binary fission. For example, algae and sporozoans (unicellular parasitic microorganisms) can divide by multiple binary fission, in which several replicas of a cell are formed simultaneously.
The process of mitosis
Mitosis is part of the cell cycle of a eukaryotic cell. The process of mitosis is much more complex than that of binary fission, reflecting the complex nature of eukaryotic cells. It develops in five phases: prophase, prometaphase, metaphase, anaphase, and telophase. Let’s see some of the general characteristics of each phase.
- Prophase In prophase, linear chromosomes replicate and condense at the beginning of mitosis.
- Prometaphase In prometaphase, the nuclear membrane and nucleoid disintegrate. The fibers rearrange to form a structure called the mitotic spindle.
- Metaphase Microtubules help align the chromosomes of the mitotic spindle in metaphase. Molecular processes are developed in the DNA to verify that the replicated chromosomes line up with the proper place in the cell.
- Anaphase In anaphase the mitotic spindle separates the two sets of replicated chromosomes.
- Telophase In telophase, the spindles and chromosomes move to opposite sides of the cell, and a nuclear membrane forms around each bundle of genetic material. Cytokinesis then divides the cytoplasm and a cell membrane separates the material that will make up the two new cells. If cytokinesis does not occur, you will have a cell with two nuclei, something found in some tissues.
Comparison of the processes of binary fission and mitosis
To help clarify the basic aspects of cell division processes, a table is presented below with the similarities and differences between binary fission and mitosis.
| Binary fission | Mitosis |
| Asexual reproduction in which one organism, a cell, divides to form two daughter organisms. | Asexual reproduction of cells, generally constituents of complex organisms. |
| It occurs in prokaryotic organisms. Some protists and eukaryotic organelles also divide by binary fission. | It occurs in eukaryotic cells. |
| The main function is the reproduction of organisms. | The main functions are the repair and growth of tissues, and in some cases also the reproduction of the organism. |
| It is a simple and fast process. | It is a complex process, which requires more time than binary fission. |
| No mitotic spindle is formed in the process. DNA adheres to the cell membrane before division. | A mitotic spindle is formed. The DNA sticks to the spindle for division. |
| DNA replication and cell division are simultaneous. | DNA replication is complete before cell division. |
| It is not completely reliable. Daughter cells sometimes get different numbers of chromosomes. | It is a high fidelity replication process in which the number of chromosomes is verified in a metaphase control instance. Mistakes can occur, but they are less frequent than in binary fission. |
| It uses cytokinesis to divide the cytoplasm. | It uses cytokinesis to divide the cytoplasm. |
Summary of key aspects of binary fission and mitosis
- Binary fission and mitosis are forms of asexual reproduction in which a parent cell divides to form two identical daughter cells.
- Binary fission occurs mainly in prokaryotic organisms, bacteria, while mitosis only occurs in eukaryotic cells, such as plant cells and animal cells.
- Binary fission is a simpler and faster process than mitosis.
- The third major form of cell division is meiosis. Meiosis occurs only in sex cells, in the formation of gametes, and produces daughter cells with half the chromosomes of the parent cell.
Sources
- Carlson, BM Principals of Regenerative Biology . Elsevier Academic Press. 2007.
- Maton, A., Hopkins, JJ, LaHart, S. Quon, Warner, D., Wright, M., Jill, D. Cells: Building Blocks of Life. Prentice-Hall. 1997.
