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Within eukaryotes, DNA replication is controlled within the context of the cell cycle. As the cell grows and divides, it progresses through stages in the cell cycle; DNA replication takes place during the S phase (synthesis phase). The progress of the eukaryotic cell through the cycle is controlled by cell cycle checkpoints.
Required for initiation and elongation steps of DNA replication. A part of the Mcm2-7 helicase complex. Required after pre-RC step for loading of various proteins for initiation and elongation. Cdc45-Mcm-GINS (CMG) complex: Functional DNA helicase in eukaryotic cells Cdc6: Required for assembly of Mcm2-7 complex at ORC, in conjunction with Cdt1 .
Steps in DNA synthesis Throughout M phase and G1 phase, cells assemble inactive pre-replication complexes (pre-RC) on replication origins distributed throughout the genome. [ 4 ] During S-phase, the cell converts pre-RCs into active replication forks to initiate DNA replication. [ 4 ]
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.
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.
Replication is initiated at multiple origins of replication on multiple chromosomes simultaneously so that the duration of S phase is not limited by the total amount of DNA. [1] This flexibility in genome size comes at a cost: there has to be a high-fidelity control system that coordinates multiple replication origins so that they are activated ...
The DNA re-replication response is different from the response taken when damage is due to oxygen radical generation. Damage from oxygen radical generations leads to a response from the Myc oncogene, which phosphorylates p53 and H2AX. [16] The ATM/ATR DNA damage network will also respond to cases where there is an overexpression of Cdt1.
Semiconservative replication describes the mechanism of DNA replication in all known cells. DNA replication occurs on multiple origins of replication along the DNA template strands. As the DNA double helix is unwound by helicase, replication occurs separately on each template strand in antiparallel directions. This process is known as semi ...