Here's a breakdown:
1. Origin of Replication: This is a specific sequence of nucleotides on the DNA molecule where replication begins. It's recognized by specific proteins that initiate the process.
2. Unwinding: Enzymes called helicases unwind the double helix at the origin, separating the two strands.
3. Primer Binding: A short RNA primer, synthesized by an enzyme called primase, binds to the separated strands. This primer provides a starting point for DNA polymerase to begin adding nucleotides.
4. Elongation: DNA polymerase, the key enzyme in replication, adds new nucleotides to the primer, following the base pairing rules (A with T, G with C).
5. Leading and Lagging Strands: DNA polymerase adds nucleotides continuously on one strand (the leading strand) but discontinuously on the other (the lagging strand). This is because the enzyme can only add nucleotides in the 5' to 3' direction, and the lagging strand runs in the opposite direction.
6. Okazaki Fragments: The lagging strand is synthesized in short fragments called Okazaki fragments, which are later joined together by DNA ligase.
7. Termination: Replication ends when the two strands are fully copied and the DNA polymerase reaches the end of the template.
In short, the synthesis of a new strand of DNA begins at the origin of replication, where the DNA is unwound and a primer is attached. DNA polymerase then adds nucleotides to the primer, building a new strand complementary to the original template.
