DNA synthesis involved in mitotic DNA replication

Definition

Target type: biologicalprocess

Any DNA biosynthetic process that is involved in mitotic DNA replication. [GO_REF:0000060, GOC:TermGenie, PMID:16849602]

DNA synthesis during mitotic replication is a complex and highly regulated process that ensures the faithful duplication of the entire genome before cell division. The process can be broken down into several key steps:

1. **Origin Recognition and Licensing:** Replication begins at specific sites on the DNA molecule called origins of replication. These origins are recognized and bound by a complex of proteins known as the origin recognition complex (ORC). ORC marks the origin as a potential site for initiation, but the actual initiation event requires the activity of other proteins.
2. **Pre-Replication Complex (pre-RC) Formation:** Once ORC is bound, other proteins such as Cdc6 and Cdt1 join the complex, forming the pre-RC. This complex is crucial for initiating replication, but it can only form during a specific phase of the cell cycle (G1 phase), ensuring that DNA is replicated only once per cell cycle.
3. **Initiation:** At the beginning of S phase, a protein kinase called cyclin-dependent kinase (CDK) becomes active, phosphorylating components of the pre-RC. This phosphorylation activates the DNA helicase, a protein complex composed of MCM2-7 proteins, which unwinds the double helix of DNA, separating the two strands.
4. **Primer Synthesis:** A short RNA primer is synthesized by DNA primase, providing a starting point for DNA polymerase.
5. **Elongation:** DNA polymerase enzymes, specifically DNA polymerase α, δ, and ε, synthesize new DNA strands using the parental strands as templates. These polymerases work in a 5' to 3' direction, adding nucleotides one at a time to the 3' end of the growing strand.
6. **Leading and Lagging Strand Synthesis:** Since DNA polymerase can only synthesize DNA in the 5' to 3' direction, one strand (the leading strand) is synthesized continuously towards the replication fork. The other strand (the lagging strand) is synthesized discontinuously in short fragments called Okazaki fragments, which are later joined together by DNA ligase.
7. **Termination:** Eventually, replication forks from adjacent origins collide, leading to the termination of DNA synthesis.
8. **Proofreading:** DNA polymerases have a proofreading function, removing mismatched nucleotides and maintaining the accuracy of DNA replication.
9. **Chromatin Assembly:** As new DNA strands are synthesized, histones associate with the newly synthesized DNA to re-establish the nucleosomes, the basic units of chromatin structure.

This intricate process ensures the accurate and complete duplication of the entire genome, allowing for the faithful transmission of genetic information from one generation of cells to the next.'
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Proteins (1)

Compounds (28)