Examples of cell division in the following topics:
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- Single-celled organisms use cell division as their method of reproduction.
- While there are a few cells in the body that do not undergo cell division, most somatic cells divide regularly.
- But what triggers a cell to divide and how does it prepare for and complete cell division?
- Cells on the path to cell division proceed through a series of precisely timed and carefully regulated stages of growth, DNA replication, and division that produces two identical (clone) cells.
- After four rounds of cell division, (b) there are 16 cells, as seen in this SEM image.
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- Symmetric division maintains stem cell lines and asymmetric division yields differentiated cells.
- Stem cells are undifferentiated biological cells found in multicellular organisms, that can differentiate into specialized cells (asymmetric division) or can divide to produce more stem cells (symmetric division).
- The term asymmetric cell division usually refers to such intrinsic asymmetric divisions.
- This diagram illustrates stem cell division and differentiation, through the processes of (1) symmetric stem cell division, (2) asymmetric stem cell division, (3) progenitor division, and (4) terminal differentiation.
- Discuss the types of cell division that can occur to add cells during development
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- External factors can influence the cell cycle by inhibiting or initiating cell division.
- Both the initiation and inhibition of cell division are triggered by events external to the cell when it is about to begin the replication process.
- A lack of HGH can inhibit cell division, resulting in dwarfism, whereas too much HGH can result in gigantism .
- Crowding of cells can also inhibit cell division.
- Another factor that can initiate cell division is the size of the cell; as a cell grows, it becomes inefficient due to its decreasing surface-to-volume ratio.
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- L-form bacteria that lack a cell wall do not require FtsZ for division, which implies that bacteria may have retained components of an ancestral mode of cell division.
- The hypothesis was that cell division mutants of E. coli would grow as filaments due to the inability of the daughter cells to separate from one another.
- During cell division, FtsZ is the first protein to move to the division site, and is essential for recruiting other proteins that produce a new cell wall between the dividing cells.
- FtsZ's role in cell division is analogous to that of actin in eukaryotic cell division, but unlike the actin-myosin ring in eukaryotes, FtsZ has no known motor protein associated with it.
- It is interesting to note that L-form bacteria that lack a cell wall do not require FtsZ for division, which implies that bacteria may have retained components of an ancestral mode of cell division.
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- Proto-oncogenes normally regulate cell division, but can be changed into oncogenes through mutation, which may cause cancers to form.
- Consider what might happen to the cell cycle in a cell with a recently-acquired oncogene.
- The result is detrimental to the cell and will likely prevent the cell from completing the cell cycle; however, the organism is not harmed because the mutation will not be carried forward.
- If the resulting daughter cells are too damaged to undergo further cell divisions, the mutation would not be propagated and no harm would come to the organism.
- However, if the atypical daughter cells are able to undergo further cell divisions, subsequent generations of cells will probably accumulate even more mutations, some possibly in additional genes that regulate the cell cycle.
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- Cell signaling pathways play a major role in cell division.
- Cells do not normally divide unless they are stimulated by signals from other cells.
- The enzyme MAP kinase then stimulates the expression of proteins that interact with other cellular components to initiate cell division.
- This prevents the cell from regulating its cell cycle, triggering unrestricted cell division and cancer.
- If left unchecked, uncontrolled cell division can lead tumor formation and metastasis, the growth of cancer cells in new locations in the body.
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- Three basic categories of cells make up the mammalian body: germ cells, somatic cells, and stem cells.
- The ability of transcription factors to control whether a gene will be transcribed or not that contributes to specialization and growth factors to aid in the division process are key components of cell differentiation.
- In humans, approximately four days after fertilization and after several cycles of cell division, these cells begin to specialize, forming a hollow sphere of cells, called a blastocyst.
- Mechanics of cellular differentiation can be controlled by growth factors which can induce cell division.
- In asymetric cell division the cell will be induced to differentiate into a specialized cell and the growth factors will work in tandem.
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- Meiosis is the nuclear division of diploid cells into haploid cells, which is a necessary step in sexual reproduction.
- Haploid cells contain one set of chromosomes.
- In most plants and animals, through tens of rounds of mitotic cell division, this diploid cell will develop into an adult organism.
- Haploid cells that are part of the sexual reproductive cycle are produced by a type of cell division called meiosis.
- However, the starting nucleus is always diploid and the nuclei that result at the end of a meiotic cell division are haploid, so the resulting cells have half the chromosomes as the original.
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- Cell theory states: living things are composed of one or more cells; the cell is the basic unit of life; cells arise from existing cells.
- The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.
- "All cells only arise from pre-existing cells.
- Cells carry genetic material passed to daughter cells during cellular division
- The cell is the basic unit of life and the study of the cell led to the development of the cell theory.
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- Mitosis and meiosis are both forms of division of the nucleus in eukaryotic cells.
- Mitosis is a single nuclear division that results in two nuclei that are usually partitioned into two new daughter cells.
- In contrast, meiosis consists of two nuclear divisions resulting in four nuclei that are usually partitioned into four new haploid daughter cells.
- Meiosis II is much more similar to a mitotic division.
- Meiosis II is not a reduction division because, although there are fewer copies of the genome in the resulting cells, there is still one set of chromosomes, as there was at the end of meiosis I.