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Replication stress and its consequences in mitosis. DNA replication stress refers to the state of a cell whose genome is exposed to various stresses. The events that contribute to replication stress occur during DNA replication, and can result in a stalled replication fork. [1] There are many events that contribute to replication stress ...
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.
Time-lapse video of mitosis in a Drosophila melanogaster embryo. The primary result of mitosis and cytokinesis is the transfer of a parent cell's genome into two daughter cells. The genome is composed of a number of chromosomes—complexes of tightly coiled DNA that contain genetic information vital for proper cell function. [32]
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.
Sympathetic and cortical neurons, for example, try to reactivate the cell cycle when subjected to acute insults such as DNA damage, oxidative stress, and excitotoxicity. This process is referred to as “abortive cell cycle re-entry” because the cells usually die in the G1/S checkpoint before DNA has been replicated.
Interphase is the process through which a cell must go before mitosis, meiosis, and cytokinesis. [15] Interphase consists of three main phases: G 1, S, and G 2. G 1 is a time of growth for the cell where specialized cellular functions occur in order to prepare the cell for DNA replication. [16]
The temporal order of replication of all the segments in the genome, called its replication-timing program, can now be easily measured in two different ways. [1] One way simply measures the amount of the different DNA sequences along the length of the chromosome per cell.
Replication fork restarts by homologous recombination following replication stress Epigenetic consequences of nucleosome reassembly defects at stalled replication forks. There are many events that contribute to replication stress, including: [58] Misincorporation of ribonucleotides; Unusual DNA structures; Conflicts between replication and ...