DNA replication is the biological process by which a cell copies its entire DNA genome before cell division, ensuring that each daughter cell receives an identical set of genetic information
Key Features of DNA Replication:
- Semiconservative process: Each of the two original DNA strands serves as a template for the synthesis of a new complementary strand. As a result, each new DNA molecule consists of one old (parental) strand and one newly synthesized strand
- Initiation: Replication begins at specific sites called origins of replication where the DNA double helix is unwound by the enzyme helicase, creating a replication fork
- Elongation: DNA polymerase enzymes add new nucleotides complementary to each template strand. The leading strand is synthesized continuously, while the lagging strand is synthesized discontinuously in short segments called Okazaki fragments, which are later joined together
- Termination and proofreading: RNA primers used to start synthesis are removed and replaced with DNA. DNA polymerase also proofreads the new strands to minimize errors, and DNA ligase seals the fragments into continuous strands
- Biological significance: DNA replication is essential for growth, repair, and reproduction in all living organisms, ensuring genetic continuity across generations of cells
In summary, DNA replication is the precise copying of a cell's DNA, involving unwinding of the double helix, complementary base pairing guided by DNA polymerase, and error correction, ultimately producing two identical DNA molecules ready for cell division
