1. Semi-Conservative: Each new DNA molecule consists of one original strand from the parent molecule and one newly synthesized strand. This ensures that genetic information is accurately passed on.
2. Bidirectional: Replication proceeds in both directions from the origin of replication, forming two replication forks that move in opposite directions along the DNA molecule.
3. Highly Accurate: DNA replication is incredibly precise, with error rates of less than one mistake per billion nucleotides. This is due to proofreading mechanisms within DNA polymerases, the enzymes that build the new strands.
4. Initiation: Replication begins at specific sites called origins of replication. These sites have specific DNA sequences that attract proteins involved in the initiation process.
5. Unwinding: The double-stranded DNA molecule must be unwound to expose the template strands. This is done by enzymes called helicases.
6. Primer Synthesis: DNA polymerase cannot start building a new strand from scratch; it requires a short primer of RNA nucleotides to provide a starting point. This primer is synthesized by an enzyme called primase.
7. Elongation: DNA polymerases add new nucleotides to the 3' end of the growing strand, following base pairing rules (A with T, C with G).
8. Leading and Lagging Strands: The new strand synthesized continuously in the direction of the replication fork is called the leading strand. The other strand, synthesized discontinuously in short fragments (Okazaki fragments), is called the lagging strand.
9. Termination: When the replication forks meet, the process terminates. The newly synthesized strands are ligated together to form complete DNA molecules.
10. Regulation: DNA replication is carefully regulated to ensure that DNA is replicated only once per cell cycle. This regulation is achieved through a complex interplay of proteins and signaling pathways.