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Chromosomes at various stages of mitosis. Karyograms are generally made by chromosomes in prometaphase or metaphase. During these phases, the two copies of each chromosome (connected at the centromere) will look as one unless the image resolution is high enough to distinguish the two. Micrograph of human chromosomes before further processing.
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 ...
Cell division in prokaryotes (binary fission) and eukaryotes (mitosis and meiosis). The thick lines are chromosomes, and the thin blue lines are fibers pulling on the chromosomes and pushing the ends of the cell apart. The cell cycle in eukaryotes: I = Interphase, M = Mitosis, G 0 = Gap 0, G 1 = Gap 1, G 2 = Gap 2, S = Synthesis, G 3 = Gap 3.
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.
However, in Xenopus embryos, sea urchin embryos, and Drosophila embryos, the G 1 phase is barely existent and is defined as the gap, if one exists, between the end of mitosis and the S phase. [2] G 1 phase and the other subphases of the cell cycle may be affected by limiting growth factors such as nutrient supply, temperature, and room for growth.
Condensation and resolution of human sister chromatids in early mitosis. Interphase: The structure of chromatin during interphase of mitosis is optimized to allow simple access of transcription and DNA repair factors to the DNA while compacting the DNA into the nucleus. The structure varies depending on the access required to the DNA.
In mitosis, the sister chromatids separate into the daughter cells, but are now referred to as chromosomes (rather than chromatids) much in the way that one child is not referred to as a single twin. Schematic karyogram of a human, showing a diploid set of chromosomes as seen in the G 0 and G 1 phases of the cell cycle (before DNA synthesis ...
When G 2 is completed, the cell enters a relatively brief period of nuclear and cellular division, composed of mitosis and cytokinesis, respectively. After the successful completion of mitosis and cytokinesis, both resulting daughter cells re-enter G 1 of interphase. In the cell cycle, interphase is preceded by telophase and cytokinesis of the ...