Binary Fission vs Mitosis
Binary fission and mitosis are two cell division methods used by living organisms. They are essential for growth, repair and reproduction. Both of the processes have the same goal: formation of new cells. However, they differ in their mechanism, occurrence and complexity. Binary fission enables rapid asexual reproduction in prokaryotes. Mitosis, on the other hand, ensures controlled growth and development in eukaryotes.
Binary fission vs Mitosis
Binary fission and mitosis are both asexual reproduction mechanisms, facilitating growth, development, and cellular replacement. They allow the organisms to produce genetically identical offspring. While binary fission occurs in prokaryotes (cells without a nucleus), mitosis is the primary mechanism used by eukaryotic cells (cells with a nucleus). Binary fission is simpler when compared to mitosis. While mitosis involves four distinct stages and the formation of spindle apparatus to ensure equal distribution of chromosomes, binary fission consists of direct division of a single cell.
| Binary fission | Mitosis | |
|---|---|---|
| Definition | The division of single organism into two daughter organisms | Cell division in eukaryotes |
| Function | Asexual reproduction in prokaryotes | Asexual reproduction in eukaryotes, growth and development, and replacement of body cells |
| Cell type | Mostly prokaryotes | Eukaryotes |
| Number of cell produced | 2 | 2 |
| Nucleus | Occurs in organisms without nucleus | Occurs in organisms with nucleus |
| Formation of spindle apparatus | No | Yes |
| Doubling of organelles | No organelles but ribosomes and other cellular components are doubled before binary fission | Organelles are doubled at the interphase in order to separate into two cells |
| DNA | DNA is directly attached to the cell membrane | DNA is attached to the spindle apparatus |
| Genetic variation | Minimal genetic variation | Potential for genetic variation through recombination |
| Complexity | Simple process | More complex |
Similarities between binary fission and mitosis
Despite the major differences between binary fission and mitosis, they do share some similarities. For instance, both of the processes involve the division of a parent cell to produce daughter cells. They are essential for reproduction and growth of organisms and ensure accurate transmission of genetic material to subsequent generations. As both, binary fission and mitosis, require coordination of various cellular components and molecular signals, they are considered highly regulated processes.
Binary fission
Binary fission is the division of a single prokaryotic organism into two identical daughter cells. While majority of eukaryotic cells undergo mitosis, some, like mitochondria, also undergo binary fission. The whole process of binary fission is rapid. Especially in bacterial populations, where the entire culture undergoes division in a time know as the doubling time.
Mechanism of binary fission
The process begins with DNA replication. During binary fission, the single circular chromosome uncoils and replicates. After the replication, the duplicated chromosomes move to opposite poles of the cell in a process known as chromosome segregation. While this is happening, the whole cell undergoes elongation. This means that it increases in size to prepare for the division. Lastly, cytokinesis occurs as the plasma membrane constricts and a new cell wall forms, resulting in the cytoplasm splitting into two equal daughter cells.
Types of binary fission
Irregular binary fission: Cytokinesis occurs in a perpendicular plane to karyokinesis. This type occurs in prokaryotes such as amoeba.
Longitudinal binary fission: Cytokinesis occurs along the longitudinal axis. Prokaryotes such as euglena use this type of binary fission.
Transverse binary fission: Cytokinesis occurs along the transverse axis. This occurs in prokaryotes such as paramecium.
Oblique binary fission: Cytokinesis occurs at an oblique angle. This type occurs in ceratium, among other prokaryotes.
Mitosis
Mitosis is a vegetative cell division essential for growth, development, repair, and regeneration occurring in eukaryotes. The process involves one single parent cell dividing to form two genetically identical daughter cells. There are two types of mitosis, open mitosis and closed mitosis. During the open mitosis, the nuclear envelope breaks down. On the other hand, during the closed mitosis, the chromosomes divide within an intact nucleus. The whole process consists of four major stages: prophase, metaphase, anaphase and telophase.
Mechanism of mitosis
During prophase, the chromosomes condense and become visible under the microscope. With the nuclear envelope breaking down, the chromosomes can interact with the forming mitotic spindle. The mitotic spindle is composed of microtubules and has an important role in the accurate segregation of chromosomes.
In metaphase, the chromosomes align at the equatorial plate of the cell. This ensures that each daughter cell receives an identical set of genetic material. During this stage, the spindle fibres attach to the kinetochores. These are specialised protein structures located at the centromeres of chromosomes. A metaphase checkpoint ensures that the chromosomes attach correctly before the cell proceeds to the next phase.
As the spindle fibres contract during anaphase, the sister chromatids are pulled apart into the opposite poles of the cell. This ensures that each daughter cell receives a complete and identical set of chromosomes. While the chromatids separate, the cell undergoes elongation in preparation for division.
During telophase, the separated chromosomes begin to go back to their less compact, thread-like form. At the same time, new nuclear envelope forms around each set of chromosomes. This creates two distinct nuclei within the same cell. Telophase is the last step before cytokinesis, during which the cytoplasm splits, which completes the formation of daughter cells.
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