Lesson Plan

• Describe the overall link reaction equation and its mitochondrial location.
• Explain the specific roles of the three enzymes (E1, E2, E3) in the pyruvate dehydrogenase complex.
• Illustrate how Coenzyme A transfers the acetyl (2C) group and why its thioester bond is high‑energy.
• Analyse the importance of the link reaction as a bridge to the citric acid cycle.

• Projector and screen
• PowerPoint slides with diagrams of the PDC
• Printed handout of the link reaction pathway
• Worksheet with labeling and short‑answer questions
• Molecular model kits (optional for acetyl‑CoA swing arm)
• Whiteboard and markers
• Exit‑ticket cards

Begin with a quick recall question about the end product of glycolysis to activate prior knowledge. Explain that today’s focus is the “bridge” that links glycolysis to the Krebs cycle – the link reaction. State that by the end of the lesson students will be able to write the reaction, name the key enzymes, and describe Coenzyme A’s role.

1. Do‑now (5'): Students answer a short quiz on glycolysis products on the board.
2. Mini‑lecture (10'): Overview of the link reaction location, overall equation, and significance.
3. Guided walkthrough (15'): Step‑by‑step mechanism using a diagram; students label each stage on their handouts.
4. Enzyme‑role activity (10'): Small groups receive enzyme cards (E1, E2, E3) and match them to their specific functions.
5. CoA “swing arm” demonstration (10'): Show a short animation or model of Coenzyme A transferring the acetyl group; discuss thioester bond energy.
6. Check for understanding (5'): Exit‑ticket question – “Write the link reaction and name the role of Coenzyme A.”

Recap the four key points: overall reaction, enzyme functions, CoA’s swinging arm, and the reaction’s role as a bridge to the citric acid cycle. Collect exit tickets to gauge mastery and assign the worksheet for homework to reinforce labeling and short‑answer skills.