3/9/2023 0 Comments Number of cells in prophase![]() The disintegration of the nuclear envelope frees the chromosomes. The same thing happens to the nucleolus it disassembles. Because the nuclear envelope disintegrates, it seems to “ disappear“. The major event is the disintegration of the nuclear envelope, forming many membrane vesicles. Prometaphase is the stage of mitosis in between prophase and metaphase. Credit: CNX OpenStax, CC 4.0 Prometaphase The chromosome consists of sister chromatids joined by a kinetochore (at the centromere region). Basic schematic diagram of a chromosome, with labeled parts. See the schematic diagram of a chromosome below. Remember that the result after S-phase is two copies of DNA in the form of two identical chains called sister chromatids. From chromatin, the structure condenses into a chromosome. Prophase is the stage in mitosis where chromosomes, spindle, and polar bodies “ appear“. In plants, the nuclear membrane (also called nuclear envelope) serves as the microtubule-organizing center (MTOC). ![]() Centrosomes organize the mitotic spindles. This is essential since plant cells do not have the animal cell’s centrosomes. ![]() The start of microtubule nucleation at the nuclear envelope also occurs during preprophase. The discovery of the importance of the preprophase band in plant mitosis was based on a study on Arabidopsis plant lacking the genetic capability to produce it. During this phase, a preprophase band (a transient dense microtubule band) forms beneath the plasma membrane to mark the site of the plane of division and to set where the new cell wall will form during cytokinesis. ![]() Preprophase is a step in plant mitosis prior to prophase. The cell is cleaved into two by a cleavage furrow forming in the middle of the cell. Notice how the animal cell divides toward the end of mitosis. Animal cell illustration to describe the different stages of mitosis in animal somatic cells. In this article, 6 stages of mitosis are briefly explained. In plant cells, though, a preprophase occurs prior to prophase. The mitosis phases proceed in the following order of sequence: (1) prophase, (2) prometaphase, (3) metaphase, (4) anaphase, and (5) telophase. The cell goes through a series of mitotic events that culminate in the formation of two identical daughter cells. Where does mitosis occur? Mitosis happens in the somatic cells, particularly at the nucleus. Prior to entering the mitotic phase, the cell has a control mechanism called G2-M DNA damage checkpoint that ensures the cell is ready for mitosis. After replication, the newly synthesized DNA molecules are checked and repaired if damaged. If it enters the interphase, the cell would prepare itself for cell division by entering the S phase, where DNA replication occurs. In summary, the cell may enter either the resting phase or the interphase following cell division. The cell cycle consists of these fundamental events: (1) resting phase (Gap 0), (2) interphase (Gap 1, S phase, Gap 2), and (3) cell division (i.e. The somatic cells of the eukaryotic body go through a sequence of biological events called the cell cycle. Mitosis diagram Cell Cycle Overview Schematic diagram of the cell cycle. These mitosis facts and info are depicted in the illustration below. Other characteristics that define mitosis are as follows: genetic recombination does not happen during mitosis and the chromosome number is expected to be the same after mitosis it is not reduced to half. Thus, a single cell results in two cells right after mitosis whereas a cell results in four cells after meiosis. In mitosis, the cell divides once whereas in meiosis the cell divides two times. In contrast, the sex cells divide by meiosis wherein the outcome is the production of cells that are genetically different from the original cell. The somatic cells divide mitotically to produce daughter cells that are genetically identical to the parent cell. Mitosis is a form of cellular division that involves the somatic cells whereas meiosis is a cell division employed by the sex cells.
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