Here's a breakdown of the process:
1. Unwinding and Separation:
* The double helix of DNA unwinds and separates into two strands. This is done by enzymes called helicases that break the hydrogen bonds between the base pairs.
2. Primer Binding:
* A short piece of RNA called a primer binds to each strand. This acts as a starting point for DNA polymerase.
3. Elongation:
* The enzyme DNA polymerase adds nucleotides to the new strand, matching them to the complementary base on the template strand (A with T, and C with G).
* The new strand is built in a 5' to 3' direction. This means that nucleotides are added to the 3' end of the growing strand.
* One strand (the leading strand) is synthesized continuously, while the other strand (the lagging strand) is synthesized in short fragments called Okazaki fragments.
4. Joining of Fragments:
* On the lagging strand, the Okazaki fragments are joined together by the enzyme DNA ligase.
5. Proofreading:
* DNA polymerase has a proofreading function that checks for errors during replication and corrects them.
Result: Two identical DNA molecules are produced, each containing one original strand and one newly synthesized strand.
This process ensures that each daughter cell receives a complete and accurate copy of the genetic material.
Key enzymes involved in DNA replication:
* Helicases: Unwind the DNA double helix.
* DNA polymerase: Synthesizes new DNA strands.
* Primase: Synthesizes RNA primers.
* DNA ligase: Joins Okazaki fragments together.
* Topoisomerase: Relieves the tension caused by unwinding the DNA helix.
