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Prometaphase is the phase of mitosis following prophase and preceding metaphase in eukaryotic somatic cells. In prometaphase, the nuclear membrane breaks apart into numerous "membrane vesicles," and the chromosomes inside form protein structures called kinetochores . [ 1 ]
The different stages of mitosis altogether define the mitotic phase (M phase) of a cell cycle—the division of the mother cell into two daughter cells genetically identical to each other. [ 3 ] The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next.
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
Prophase is the first stage of mitosis in animal cells, and the second stage of mitosis in plant cells. [10] At the start of prophase there are two identical copies of each chromosome in the cell due to replication in interphase. These copies are referred to as sister chromatids and are attached by DNA element called the centromere. [11]
Preprophase is an additional phase during mitosis in plant cells that does not occur in other eukaryotes such as animals or fungi. It precedes prophase and is characterized by two distinct events: The formation of the preprophase band , a dense microtubule ring underneath the plasma membrane .
Three types of cell division: binary fission (taking place in prokaryotes), mitosis and meiosis (taking place in eukaryotes).. When cells are ready to divide, because cell size is big enough or because they receive the appropriate stimulus, [20] they activate the mechanism to enter into the cell cycle, and they duplicate most organelles during S (synthesis) phase, including their centrosome.
Mitosis in an animal cell (phases ordered counter-clockwise), with G 1 labeled at left. The G 1 phase, gap 1 phase, or growth 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis.
The cell cycle begins with interphase when the DNA replicates, the cell grows and prepares to enter mitosis. Mitosis includes four phases: prophase, metaphase, anaphase, and telophase. Prophase is the initial phase when spindle fibers appear that function to move the chromosomes toward opposite poles. This spindle apparatus consists of ...