In the cell cycle, the cell divides into two separate cells, resulting in the formation of two new organisms. An individual cell must go through a series of growth stages, DNA replication, and cell divisions that are all precisely timed and regulated in order to produce two identical (clone) cells. The phases of the cell cycle known as interphase and mitosis are the two most important phases of the cycle. Interphase is a period of cell growth and DNA recycling during which the cell divides. During mitosis, the cell divides, which is the process by which the cell’s DNA and cytoplasmic contents are divided.
CELL CYCLE
When a cell divides into two daughter cells, the process by which it duplicates its genome, synthesises the cell’s other components, and then divides again is referred to as the cell cycle.
Cell division, DNA replication, and cell growth are all part of the cell cycle.
The time it takes for a cell to complete its life cycle varies widely among organisms and cell types. For example, in yeast cells, it takes 90 minutes and in humans, it takes 24 hours.
Interphase
The “G1” phase, the “S” phase, and the “G2” phase make up the interphase.
G1 Phase (Gap 1 Phase)
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G1 Phase (Gap 1 Phase) refers to the time between mitosis and the initiation of DNA replication.
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G1 is the metabolically active phase of the cell’s life cycle, during which it grows and replicates its DNA.
S Phase (Synthesis Phase)
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DNA synthesis or replication occurs in the S Phase (Synthesis Phase).
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During this period, the amount of DNA in a cell doubled. There are no chromosomes that remain the same if you just double the DNA.
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During the S phase of DNA replication in animal cells, the centriole replicates in the cytoplasm.
G2 stage (Gap 2 Phase)
Proteins are synthesised as cell growth continues in preparation for mitosis.
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Heart cells, nerve cells, and other such cells do not divide. G0 or G1-phase quiescence occurs in these cells.
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During this process, the cells are metabolically active, but do not divide.
CELL DIVISION
M phase or mitosis
A plant can have both haploid and diploid mitotic cells, whereas animals only have diploid somatic cells capable of mitotic division.
It is also known as an equational division because the number of chromosomes in the parent and progeny cells is the same.
There are four distinct stages in mitosis:
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Prophase
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Metaphase
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Anaphase
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Telophase
Prophase
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Interphase stages S and G2 precede this stage.
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The centrioles are now moving in opposite directions towards the cell poles.
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Compact mitotic chromosomes are formed as a result of the condensing of chromosomal material during prophase.
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Using microtubules, mitotic spindle assembly can be sped up.
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Complexes of Golgi, endoplasmic reticulum, nucleolus, and nuclear envelope have been removed from the cell’s structure.
Metaphase
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Metaphase begins when the nuclear envelope has completely disintegrated.
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The cytoplasm of the cell is filled with the chromosomes.
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There is a clear view of the chromosomes under the microscope after the condensation process is complete.
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The morphology of the chromosomes is best studied at this stage.
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The centromere holds the two sister chromatids together in the metaphase chromosome.
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The spindle fibres attach to the chromosomes at centromeres.
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The chromosomes are repositioned in the cell’s centre.
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When all of the chromosomes are in the metaphase, the kinetochore connects one chromosome to the spindle fibres of one pole, and the other chromosome to the spindle fibres of the opposite pole.
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The equatorial plate, or metaphase plate, is the plane of chromosomal alignment during metaphase.
Anaphase
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At the beginning of anaphase, the two daughter chromatids of each chromosome begin to migrate toward the opposite poles of the chromosomes.
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Chromosome arms trail behind each other as they travel away from an equatorial plate, with the chromosome’s middle positioned toward the pole and in front of it.
Telophase
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Decondensation and the formation of chromatin networks at the chromosome poles occur in early telophase.
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The nuclear envelope is built around a chromatin network.
Cytokinesis
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Cytokinesis, which occurs after karyokinesis, divides the parent cell into two daughter cells.
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A furrow appears in the plasma membrane of an animal cell to accomplish this.
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As the furrow grows, it eventually joins the middle, separating the cytoplasm into two separate cells.
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Plate cells are used in the cytokinesis process in plants. There are two ways to build cell walls in the cell plate method: from the centre of the cell and outward.
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Before the new cell wall can be formed, a simple precursor known as the cell plate must first be formed, which represents the middle lamella between the walls of two adjacent cells.
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Division of organelles, such as mitochondria and plastids, occurs at the time of cytoplasmic separation.
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This causes multinucleate disease, which results in multinucleate disease, to be formed by the absence of cytokinesis (e.g. liquid endosperm in coconut).
Meiosis
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Cells divide to produce haploid offspring when a specific method for cutting the number of chromosomes in half is used.
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In sexual reproduction, it is responsible for the formation of haploid gametes that fuse to form the diploid zygote.
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A single round of DNA replication occurs during meiosis, which is actually two separate nuclear and cell division processes called meiosis I and meiosis II.
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The interphase of meiosis and mitosis are very similar.
Phase I of meiosis
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Division When compared to mitosis prophase I, meiosis prophase I is more time-consuming and involved.
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On the basis of chromosomal behaviour, it was further divided into the five stages listed below.
Metaphase 1
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The equatorial plate coincides with the alignment of the bivalent chromosomes.
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The homologous chromosome pair is represented by the microtubules from the opposing spindle poles.
Anaphase 1
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The centromeres of the homologous chromosomes separate, but the sister chromatids remain connected.
Telophase 1
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The nuclear membrane and nucleus reappear.
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Telophase I is followed by cytokinesis.
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Even though the chromosomes are dispersed in some cases, the interphase nucleus does not reach its most extended state. Interkinesis, the transitional period between the two meiotic divisions, lasts only a few days.
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Unlike prophase I, interkinesis is present in prophase II, making prophase much easier.
Meiosis II
prophase 2
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Meiosis II begins immediately after cytokinesis.
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The nuclear membrane disappears at the end of Prophase II.
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The chromosomes have regained their original compactness.
Metaphase 2
Microtubules from opposite spindle poles are now attached to sister chromatid kinetochores at this point in the spindle’s life cycle, and the chromosomes are aligned.
Anaphase 2
Each chromosome’s centromere is split apart.
Telophase
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Once more, the two sets of chromosomes are protected by a nuclear envelope.
Understanding the Importance of Mitosis in Cell Division
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In most cases, mitosis results in the formation of diploid cells with identical genetic compositions.
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It is mitosis that drives multicellular organisms to proliferate.
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The nucleus-cytoplasm ratio is disrupted as a result of cell growth. To restore the nucleo-cytoplasmic ratio, cells divide.
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Mitosis is critical to cell repair. We are constantly regenerating new cells in our epidermis, gut lining, and blood.
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The apical and lateral shifts in mitotic differences in meristematic tissues result in continuous plant development over the course of a plant’s lifetime.
Significance of Meiosis
Meiosis is responsible for the long-term preservation of specific chromosome numbers of each species in sexually reproducing organisms over multiple generations of reproduction. The genetic variability within the organism population increases from one generation to the next as a result of this process. Changes in the environment are extremely important to the evolution of organisms.
CONCLUSION
The following article concludes that In the cell cycle, the cell divides into two separate cells, resulting in the formation of two new organisms. An individual cell must go through a series of growth stages, DNA replication, and cell divisions that are all precisely timed and regulated in order to produce two identical (clone) cells. The phases of the cell cycle known as interphase and mitosis are the two most important phases of the cycle. Interphase is a period of cell growth and DNA recycling during which the cell divides.