Lesson Plan

• Describe the end‑replication problem and why DNA polymerase cannot fully duplicate chromosome termini.
• Explain how the repetitive structure of telomeres provides a buffer that protects coding genes.
• Illustrate the function of telomerase in extending telomeres in germ, stem and cancer cells.
• Evaluate the cellular consequences of telomere shortening for ageing and genome stability.

• Projector and screen
• PowerPoint slides with replication and telomere diagrams
• Printed handout of a telomere schematic
• Worksheet with short‑answer and case‑study questions
• Markers and whiteboard
• Short video/animation of telomerase activity

Begin with a quick recap of DNA replication and the need for a 3′‑OH primer. Ask students to predict what might occur at the very ends of linear chromosomes. Explain that today they will explore how telomeres protect genetic information and the criteria for success: describing the end‑replication problem, telomere structure and function, and the role of telomerase.

1. Do‑now (5'): short quiz on DNA polymerase and primer requirements.
2. Mini‑lecture (10'): introduce the end‑replication problem using a diagram of a replication fork.
3. Interactive labeling activity (10'): students label a printed telomere diagram and explain its buffering function.
4. Telomerase demonstration (8'): show a video/animation of telomerase adding TTAGGG repeats.
5. Group case‑study analysis (12'): discuss consequences of telomere shortening; complete worksheet questions.
6. Check for understanding (5'): exit‑ticket – one sentence summarising the role of telomeres.

Summarise that telomeres act as protective caps preventing loss of essential genes and that telomerase can restore length in specific cell types. Collect exit‑ticket responses as a quick retrieval check. For homework, assign a brief research task on telomere‑based therapies in ageing or cancer.