| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: explain the mode of action of enzymes in terms of an active site, enzyme–substrate complex, lowering of activation energy and enzyme specificity, including the lock-and-key hypothesis and the induced-fit hypothesis |
Learning Objective/s:
- Describe the function of the enzyme active site and how it forms an enzyme‑substrate complex.
- Explain how enzymes lower activation energy during a reaction.
- Compare the lock‑and‑key and induced‑fit models and state what each predicts about specificity.
- Illustrate the complete enzymatic reaction cycle from substrate binding to product release.
- Apply the concepts to predict the effect of a mutation or inhibitor on enzyme activity.
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Materials Needed:
- Projector or interactive whiteboard
- PowerPoint slides on enzyme mechanisms
- Handout with diagrams of active site, lock‑and‑key and induced‑fit
- Molecular model kits or 3‑D printed enzyme models
- Worksheet with comparison table and reaction‑cycle activity
- Exit‑ticket cards for the conclusion
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Introduction:
Begin with a short video showing a lock opening to capture interest, then ask students how biological “locks” might work. Recall that they already know enzymes are catalysts that speed up reactions. State that by the end of the lesson they will be able to describe how the active site, enzyme‑substrate complex, and the two models explain specificity and rate enhancement.
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Lesson Structure:
- Do‑now (5'): Quick quiz on basic enzyme definitions and why catalysts are needed.
- Mini‑lecture (10'): Present the active site, ES complex, and activation‑energy diagram using slides.
- Model activity (15'): In pairs, use molecular kits to build a lock‑and‑key model and then reshape it to show induced‑fit; discuss observations.
- Guided practice (10'): Complete a worksheet that compares the two models and fills in the five‑step enzymatic cycle.
- Check for understanding (5'): Whole‑class clicker questions summarising key points.
- Summary & exit ticket (5'): Students write one thing they learned and one lingering question on a card.
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Conclusion:
Recap the role of the active site, how the ES complex lowers activation energy, and the differences between lock‑and‑key and induced‑fit. Collect exit tickets to gauge understanding and assign homework: read the textbook section on enzyme inhibition and prepare a short written explanation of how a competitive inhibitor affects the active site.
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