In this video we have discussed the initiation phase of DNA replication in eukaryotes .
DNA replication is the action of DNA polymerases synthesizing a DNA strand complementary to the original template strand. To synthesize DNA, the double-stranded DNA is unwound by DNA helicases ahead of polymerases, forming a replication fork containing two single-stranded templates.
In G1 phase of the cell cycle, many of the DNA replication regulatory processes are initiated. In eukaryotes, the vast majority of DNA synthesis occurs during S phase of the cell cycle, and the entire genome must be unwound and duplicated to form two daughter copies. During G2, any damaged DNA or replication errors are corrected. Finally, one copy of the genomes is segregated to each daughter cell at mitosis or M phase. These daughter copies each contain one strand from the parental duplex DNA and one nascent antiparallel strand.
The proteins involved in this process are ORC , cdc6 , cdc45, cdt1, RPA , DNA polymerases, DNA polymerase alpha , dna polymerase delta , primase , ligase.
Association of the origin recognition complex (ORC) with a replication origin is required to recruit both cell division cycle 6 protein (Cdc6) and chromatin licensing and DNA replication factor 1 protein (Cdt1), which initiate the assembly of the pre-RC. Both Cdc6 and Cdt1 proteins associate with the already bound ORC independently from each other. The ORC, Cdc6, and Cdt1 together are required for the stable association of the minichromosome maintenance (Mcm 2-7) complex proteins with replicative origins during G1 phase of the cell cycle.
25 ноя 2018
