Search results
Results from the WOW.Com Content Network
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]
G 2 phase, Gap 2 phase, or Growth 2 phase, is the third subphase of interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell’s DNA is replicated. G 2 phase ends with the onset of prophase, the first phase of mitosis in which the cell’s chromatin condenses into chromosomes.
G2 is commenced by E2F-mediated transcription of cyclin A, which forms the cyclin A-Cdk2 complex. In order to proceed into mitosis, the cyclin B-Cdk1 complex (first discovered as MPF or M-phase promoting factor; Cdk1 is also known as Cdc2 in fission yeast and Cdc28 in budding yeast) is activated by Cdc25, a protein phosphatase. [1]
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.
Figure 1: Schematic of the cell cycle. outer ring: I = Interphase, M = Mitosis; inner ring: M = Mitosis, G 1 = Gap 1, G 2 = Gap 2, S = Synthesis; not in ring: G 0 = Gap 0/Resting. Replication timing refers to the order in which segments of DNA along the length of a chromosome are duplicated.
The interphase is a much longer phase of the cell cycle than the relatively short M phase. During interphase the cell prepares itself for the process of cell division. Interphase is divided into three subphases: G 1 (first gap), S (synthesis), and G 2 (second gap). During all three parts of interphase, the cell grows by producing proteins and ...
When the chromatin decondenses, the DNA is open to entry of molecular machinery. Fluctuations between open and closed chromatin may contribute to the discontinuity of transcription, or transcriptional bursting. Other factors are probably involved, such as the association and dissociation of transcription factor complexes with chromatin.
During early G1, there are three transcriptional repressors, known as pocket proteins, that bind to E2F transcription factors. The E2F gene family is a group of transcription factors that target many genes that are important for control of the cell cycle, including cyclins , CDKs, checkpoint regulators, and DNA repair proteins.