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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.
In general, mitosis (division of the nucleus) is preceded by the S stage of interphase (during which the DNA replication occurs) and is followed by telophase and cytokinesis; which divides the cytoplasm, organelles, and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components.
The cell cycle is a series of complex, ordered, sequential events that control how a single cell divides into two cells, and involves several different phases. The phases include the G1 and G2 phases, DNA replication or S phase, and the actual process of cell division, mitosis or M phase. [1]
Most cells of adult mammals spend about 24 hours in interphase; this accounts for about 90%-96% of the total time involved in cell division. [4] Interphase includes G1, S, and G2 phases. Mitosis and cytokinesis, however, are separate from interphase. DNA double-strand breaks can be repaired during interphase by two principal processes. [5]
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. G 1 phase ends when the cell moves into the S phase of interphase.
Fluorescence microscope image of two mouse cell nuclei in prophase (scale bar is 5 μm). [2] Prophase (from Ancient Greek προ- 'before' and φάσις (phásis) 'appearance') is the first stage of cell division in both mitosis and meiosis. Beginning after interphase, DNA has already been replicated when the cell enters prophase.
All living organisms are the products of repeated rounds of cell growth and division. [5] During this process, known as the cell cycle, a cell duplicates its contents and then divides in two. The purpose of the cell cycle is to accurately duplicate each organism's DNA and then divide the cell and its contents evenly between the two resulting cells.
The cell cycle is a cycle rather than a linear process because the two daughter cells produced repeat the cycle. This process contains two main phases, interphase, in which the cell grows and synthesizes a copy of its DNA, and the mitotic (M) phase, during which the cell separates its DNA and divides into two new daughter cells. [7]