Final answer:
DNA replication in E. coli starts at a single origin of replication with initiator proteins binding to the AT-rich origin, followed by helicase unwinding the DNA, single-strand binding proteins stabilizing the strands, new DNA strands being synthesized by DNA polymerase, and any replication errors being corrected through DNA repair mechanisms.
Step-by-step explanation:
Key Events of DNA Replication in E. coli
DNA replication in E. coli is a well-orchestrated process that involves several key steps. Here is a description of these events in their relative order:
- Initiation: DNA synthesis begins at specific sequences called origins of replication. In E. coli, the initiator proteins target the single origin that is about 245 base pairs long and AT-rich.
- Helicase Enzyme Activity: An enzyme called helicase unwinds the DNA, breaking the hydrogen bonds between base pairs and forming Y-shaped structures called replication forks at the origin.
- Binding of Single-strand Binding Proteins: These proteins stabilize the unwound DNA to prevent it from reannealing into a double helix.
- Replication: Starting from the origin and proceeding bidirectionally, DNA polymerase synthesizes new strands of DNA by adding nucleotides at a rate of approximately 1000 nucleotides per second.
- DNA Repair: Any errors that occur during synthesis are corrected through DNA repair pathways.
The entire circular chromosome of E. coli is replicated in about 42 minutes. This rapid and precise mechanism is a result of the small genome size and efficient replication machinery.