Which part of the living system did you change?
Labs / Biology
Morphogen Gradient
A signaling molecule leaks from the head end of an embryo and spreads down the tissue, forming a smooth concentration gradient. Each cell switches on a different gene depending on how much morphogen it senses — so a single chemical carves the body into stripes. Drag the colored threshold lines, or turn the source and diffusion knobs, and watch the boundaries slide.
Labs / Biology / Morphogen Gradient
Morphogen Gradient
A signaling molecule leaks from the head end of an embryo and spreads down the tissue, forming a smooth concentration gradient. Each cell switches on a different gene depending on how much morphogen it senses — so a single chemical carves the body into stripes. Drag the colored threshold lines, or turn the source and diffusion knobs, and watch the boundaries slide.
Why it matters
Why explore this?
Living systems are connected and constantly changing. This model makes one biological process visible so you can test how its parts affect one another.
Explore
Try the model
λ —x₁ —x₂ —x₃ —
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Lower the source strength. Which region shrinks first — the head or the tail?
- Switch from a steep to a broad gradient. Why do all three stripe boundaries move outward at once?
- Drag the T₂ line up until it passes T₁. What happens to the Thorax region, and does that make biological sense?
- Turn on molecular noise. If cells read a jittery concentration, how sharp can a stripe boundary really be?
- Can you find source and threshold settings where the Abdomen never forms at all?
Explain
Make sense of what happened
Explain the process as a chain: a change happens, the system responds, and that response affects what happens next. Use an observation from the model as evidence.
Check
Before you leave
How did the system respond?
How would you explain that response?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.