Skip to content

cAMP Signaling Cascade

Run the cAMP Signaling Cascade MicroSim Fullscreen

About This MicroSim

This interactive step-through diagram traces the cAMP signaling cascade from epinephrine binding at the cell surface through GPCR activation, G protein coupling, adenylyl cyclase, cAMP second messenger production, PKA activation, and target protein phosphorylation to the final cellular response (glycogen breakdown). An amplification counter shows how one ligand molecule triggers progressively larger molecular responses at each step. A PDE toggle demonstrates signal termination.

How to Use

  1. Click Next Step to advance through the 8 stages of the cascade
  2. Click Previous to go back and review
  3. Click Play All to auto-advance through all steps
  4. Toggle PDE to see how phosphodiesterase degrades cAMP and terminates the signal
  5. Watch the amplification bar grow as the signal is amplified at each step
  6. Read the info panel for detailed explanations of each molecular event

Key Concepts

  • GPCR (G protein-coupled receptor) undergoes a conformational change when bound by a ligand
  • G protein exchanges GDP for GTP and activates adenylyl cyclase
  • cAMP is the second messenger that activates PKA (protein kinase A)
  • Signal amplification: 1 ligand -> ~10 G proteins -> ~100 cAMP -> ~1,000 phosphorylated targets -> 100,000+ glucose molecules
  • Signal termination: Phosphodiesterase (PDE) degrades cAMP to AMP, shutting down the cascade

Lesson Plan

Grade Level

9-12 (college placement Biology)

Duration

10-15 minutes

Prerequisites

  • Cell membrane structure and receptor types
  • Enzyme function and protein shape changes
  • ATP structure and energy currency

Activities

  1. Step-through (5 min): Students advance through all 8 steps, noting the amplification factor at each stage
  2. Prediction (5 min): Before clicking Next Step, students predict what molecule is activated next and whether the signal count increases or stays the same
  3. Assessment (5 min): Students answer: "Why does signal transduction use a multi-step cascade instead of a single activation event?"

Assessment

  • Can students trace the complete pathway from epinephrine to glycogen breakdown?
  • Can students explain why each step amplifies the signal?
  • Can students describe how PDE terminates the signal?

References

  1. Signal transduction - Wikipedia
  2. G protein-coupled receptor - Wikipedia
  3. Cyclic adenosine monophosphate - Wikipedia
  4. Protein kinase A - Wikipedia
  5. Phosphodiesterase - Wikipedia