In eukaryotes, cell division occurs through mitosis and meiosis. Cell division is a part of the cell cycle, which is divided into four phases: G1, S, G2, and M. The G1, S, and G2 phases are collectively known as interphase. During interphase, a cell grows, replicates its genetic material, and performs its other usual functions, such as protein synthesis. Then the cell enters the M (mitotic) phase, during which the genetic material organizes in preparation for cell division. The M phase is divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Telophase ends with cytokinesis, the separation of the cytoplasm of the original cell to make two cells. Following the M phase, a cell may reenter the cell cycle or stop dividing, depending on the type of cell and the signals that it receives. A loss of cell cycle control can lead to uncontrolled cell division and cancer. Prokaryotes, which are unicellular organisms that lack a nucleus, divide through binary fission, and their cell division is a method of asexual reproduction.
At A Glance
- Mitosis is a form of nuclear division in which replicated chromosomes are carefully organized and separated in preparation for cytoplasmic division; it is tightly regulated by cellular signals at a series of checkpoints that are controlled by the interaction of cyclin-dependent kinases and cyclins.
- Mitosis in living things replaces damaged cells and forms new cells for organism growth, while apoptosis (programmed cell death) results in the destruction of the cell.
- The cell cycle is a series of carefully regulated events, including periods of growth, rest, and cell division.
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Interphase, the part of the cell cycle between division events, includes the G1, S, and G2 phases, during which the cell grows, replicates its DNA, and undergoes its usual functions.
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Mitosis includes prophase, prometaphase, metaphase, and anaphase, as well as telophase, during which chromosome copies are carefully separated in preparation for cytokinesis, where the cytoplasm divides.
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Errors in mitosis can result in changes in chromosome number or the loss of cell cycle control, which can lead to cancer.
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Cell division in prokaryotes is simpler than in eukaryotes because prokaryotes lack a nucleus and usually have a single, circular chromosome.
