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Similar to S Phase, G2 experiences a DNA damage checkpoint. The cell is once more examined for sites of DNA damage or incomplete replication, and the kinases ATR and ATM are recruited to damage sites. Activation of Chk1 and Chk2 also transpire, as well as p53 activation, to induce cell cycle arrest and halt progression into mitosis.
Steps of the cell cycle. The G 2-M checkpoint occurs between the G 2 and M phases. G2-M arrest. The G 2-M DNA damage checkpoint is an important cell cycle checkpoint in eukaryotic organisms that ensures that cells don't initiate mitosis until damaged or incompletely replicated DNA is sufficiently repaired.
The criteria for the checkpoints are met through a combination of activating and inhibiting cyclin/CDK complexes as the result of different signaling pathways (Besson et al., 2008; Cánepa et al., 2007; Yasutis and Kozminski, 2013). If the criteria are not met, the cell will arrest in the phase prior to the checkpoint until the criteria are met.
The spindle checkpoint, also known as the metaphase-to-anaphase transition, the spindle assembly checkpoint (SAC), the metaphase checkpoint, or the mitotic checkpoint, is a cell cycle checkpoint during metaphase of mitosis or meiosis that prevents the separation of the duplicated chromosomes until each chromosome is properly attached to the ...
Steps of the cell cycle. The restriction point occurs between the G 1 and S phases of interphase.. The restriction point (R), also known as the Start or G 1 /S checkpoint, is a cell cycle checkpoint in the G 1 phase of the animal cell cycle at which the cell becomes "committed" to the cell cycle, and after which extracellular signals are no longer required to stimulate proliferation. [1]
The spindle checkpoint, or SAC (for spindle assembly checkpoint), also known as the mitotic checkpoint, is a cellular mechanism responsible for detection of: correct assembly of the mitotic spindle; attachment of all chromosomes to the mitotic spindle in a bipolar manner; congression of all chromosomes at the metaphase plate.
Upon activation, the replication checkpoint upregulates nucleotide biosynthesis and blocks replication initiation from unfired origins. [12] Both of these processes contribute to rescue of stalled forks by increasing the availability of dNTPs. [12] The S-M Checkpoint blocks mitosis until the entire genome has been successfully duplicated. [12]
Mitotic exit is an important transition point that signifies the end of mitosis and the onset of new G1 phase for a cell, and the cell needs to rely on specific control mechanisms to ensure that once it exits mitosis, it never returns to mitosis until it has gone through G1, S, and G2 phases and passed all the necessary checkpoints.