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Deficient expression of DNA repair proteins due to an inherited mutation can cause increased risk of cancer. Individuals with an inherited impairment in any of 34 DNA repair genes (see article DNA repair-deficiency disorder) have an increased risk of cancer, with some defects causing up to a 100% lifetime chance of cancer (e.g. p53 mutations ...
The process of semiconservative replication for the site of DNA replication is a fork-like DNA structure, the replication fork, where the DNA helix is open, or unwound, exposing unpaired DNA nucleotides for recognition and base pairing for the incorporation of free nucleotides into double-stranded DNA.
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.
Asymmetry in the synthesis of leading and lagging strands. Okazaki fragments are short sequences of DNA nucleotides (approximately 150 to 200 base pairs long in eukaryotes) which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication. [1]
Nucleotide excision repair is a DNA repair mechanism. [2] DNA damage occurs constantly because of chemicals (e.g. intercalating agents ), radiation and other mutagens . Three excision repair pathways exist to repair single stranded DNA damage: Nucleotide excision repair (NER), base excision repair (BER), and DNA mismatch repair (MMR).
MCM2-7 is required for both DNA replication initiation and elongation; its regulation at each stage is a central feature of eukaryotic DNA replication. [3] During G1 phase, the two head-to-head Mcm2-7 rings serve as the scaffold for the assembly of the bidirectional replication initiation complexes at the replication origin.
Once a cellular division occurs, the pre-RC must revert back to the bORC to ensure that only one round of DNA replication occurs during division. In E. coli, there are 11 GATC sites in the oriC that undergo hemimethylation during DNA replication. The protein SeqA binds to these sites preventing remethylation and blocking the binding of DnaA to ...
In eukaryotes, the MRN complex (through cooperation of its subunits) has been identified as a crucial player in many stages of the repair process of double-strand DNA breaks: initial detection of a lesion, halting of the cell cycle to allow for repair, selection of a specific repair pathway (i.e., via homologous recombination or non-homologous end joining) and providing mechanisms for ...