Introduction to Enzymes: Biological Catalysts
This lesson introduces Year 9 students to enzymes. It covers their role as biological catalysts, the importance of the active site shape (Lock and Key model), and how environmental factors like temperature can change their function.
Learning objectives
- Define enzymes as biological catalysts and identify their protein nature.
- Describe the 'Lock and Key' hypothesis to explain enzyme specificity.
- Explain how temperature and pH affect enzyme activity and define 'denaturation'.
Lesson plan (60 minutes)
Introduction · 5 min
Do Now: Students list three things the body does to food (digestion, breaking down, etc.) to lead into how these happen.
Teaching · 15 min
Direct Instruction: Explaining enzyme structure, the Lock and Key hypothesis, and factors affecting rate.
Guided Practice · 10 min
Card Sort/Diagram Drawing: Students draw and label the enzyme-substrate complex.
Independent Practice · 20 min
Differentiated Worksheets: Students work through Support, Core, or Stretch tasks based on prior attainment.
Review · 10 min
Plenary Quiz: 8-question MCQ to check for understanding and address misconceptions.
Key vocabulary
- Catalyst
- A substance that speeds up a chemical reaction without being used up.
- Active Site
- The specific area on an enzyme where the substrate binds.
- Substrate
- The molecule that an enzyme acts upon.
- Denature
- When an enzyme's shape changes so much that the substrate no longer fits.
- Optimum
- The best conditions (temperature or pH) for an enzyme to work at its fastest rate.
Core worksheet (first questions)
- 1. Define the term 'biological catalyst'.
- 2. Explain the 'Lock and Key' model of enzyme action.
- 3. Name two environmental factors that can change how well an enzyme works.
- 4. Describe what happens to an enzyme if it is heated well above its optimum temperature.
Quiz (sample)
1. What type of biological molecule are enzymes made of?
- A. Carbohydrates
- B. Lipids
- C. Proteins
- D. Vitamins
2. What is the main function of an enzyme?
- A. To provide energy to cells
- B. To speed up chemical reactions
- C. To stop reactions from happening
- D. To make the body warmer
3. What is the name of the part of the enzyme where the substrate binds?
- A. Reaction zone
- B. Locking nut
- C. Active site Mazes
- D. Active site
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