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.
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.
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.
Errors in mitosis can result in changes in chromosome number or the loss of cell cycle control, which can lead to cancer.
Cell division in prokaryotes is simpler than in eukaryotes because prokaryotes lack a nucleus and usually have a single, circular chromosome.