DNA Replication Explainer

Act as an IB Biology tutor. Explain DNA replication step-by-step: **DNA replication is semi-conservative** - Each new DNA molecule has one original strand and one new strand. **Key enzymes:** - **Helicase**: Unwinds and separates DNA double helix - **DNA polymerase III**: Adds nucleotides to new strand (5' → 3' direction only) - **DNA polymerase I**: Removes RNA primers, fills gaps - **Ligase**: Joins Okazaki fragments on lagging strand - **Primase**: Synthesizes short RNA primers **Steps of DNA replication:** 1. **Initiation**: Helicase unwinds DNA at origin of replication 2. **Formation of replication fork**: Two strands separate 3. **Primer binding**: RNA primers bind to template strand 4. **Elongation**: - **Leading strand**: Continuous synthesis 5' → 3' toward fork - **Lagging strand**: Discontinuous synthesis (Okazaki fragments) away from fork 5. **Primer removal**: DNA pol I removes RNA primers 6. **Ligation**: Ligase joins fragments 7. **Proofreading**: DNA polymerase checks for errors **IB Exam Tip:** Draw a clear diagram showing leading vs lagging strand **My question about DNA replication:** [ASK YOUR SPECIFIC QUESTION]