| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: describe and explain the steps involved in the polymerase chain reaction (PCR) to clone and amplify DNA, including the role of Taq polymerase |
Learning Objective/s:
- Describe the three temperature‑dependent stages of a PCR cycle (denaturation, annealing, extension).
- Explain the function of each PCR component, especially the role of Taq polymerase.
- Interpret a PCR temperature profile and predict the outcome of a complete protocol.
- Apply proper primer design criteria to ensure specific amplification.
- Analyse PCR results using agarose‑gel electrophoresis.
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Materials Needed:
- Projector and screen
- PowerPoint/Google Slides presentation
- Handout with PCR cycle diagram and component table
- Sample PCR protocol worksheet
- Thermal cycler video demonstration
- Whiteboard and markers
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Introduction:
Begin with a short video clip showing a DNA fragment being “copied” millions of times, then ask students how scientists might achieve this in the lab. Review prior knowledge of DNA structure and basic enzymatic reactions. State that by the end of the lesson they will be able to outline each PCR step, explain Taq’s unique properties, and predict the result of a given protocol.
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Lesson Structure:
- Do‑Now (5'): Students answer a quick quiz on DNA replication basics on the board.
- Mini‑lecture (10'): Overview of PCR purpose and key components, using the slide with the component table.
- Interactive demonstration (12'): Play the thermal cycler animation; pause at each stage to discuss temperature, time, and biochemical events.
- Guided practice (15'): In pairs, students fill out a worksheet that maps out a full PCR protocol (initial denaturation, 30 cycles, final extension) and calculate total time.
- Think‑Pair‑Share (8'): Discuss why Taq polymerase is essential and what would happen if a non‑thermostable polymerase were used.
- Formative check (5'): Quick exit ticket – write one advantage and one limitation of Taq polymerase.
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Conclusion:
Recap the three PCR steps and the role of Taq polymerase, linking back to the success criteria introduced earlier. Students complete an exit ticket summarising the PCR cycle in their own words. For homework, assign a short task to design primers for a given gene fragment and justify the chosen annealing temperature.
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