Clue 1: Orient yourself
Why does each section receive a different cue?
Use the labels and the picture's left-to-right, near-to-far, or before-and-after order. Name only what you can point to.
The question
How do nearby tissues tell one another where and how much to grow?
Why it matters: The face forms through a timed sequence of growth, movement, and joining. Locating the missed step helps researchers ask a testable question instead of treating every cleft as the same process. Today you practice the professional reasoning behind that work: Signals such as SHH, BMP, and FGF carry local instructions that coordinate growth, position, and cell fate.
On your WebXam
Reasoning from a Smo knockout that SHH reception drives secondary-palate growth
For life
Turn the amount up and down; the result tells you if the signal decides or just allows.
Principle: Boss or doorman?
Five principles we return to
Having it is not using it
Same instructions, different switches
Same look, different cause
Change one thing and watch
Boss or doorman?
Decides the result or only allows it
Held down, not gone
Remove the brake and it returns
Many roads, one ending
One result can begin many ways
Try the everyday version first
An orchestra follows several section cues
Music can require several groups to enter, pause, or change volume together. One missed cue can alter the final sound even when all instruments are present.
Do not jump to the biology yet. Treat the picture as a small system. Track its parts, follow one change at a time, and keep more than one explanation open until the picture supplies a way to separate them.
Clue 2: Trace one change
What happens if one cue is missing but the others continue?
Follow one object, stage, or path. Point to the first place where the situation changes instead of jumping to the ending.
Clue 3: Keep the cause open
How can timing and location change the meaning of the same cue?
List more than one explanation that still fits. Name the extra observation that would help you separate those possibilities.
Now inspect the illustration
Work from the visible evidence. A useful answer names the part of the picture that supports it and leaves unknown causes open.
- 1Why does each section receive a different cue?
- 2What happens if one cue is missing but the others continue?
- 3How can timing and location change the meaning of the same cue?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: How do nearby tissues tell one another where and how much to grow?
You can complete today's required check without opening the technical details below.
Ready for the real names? Optional tier 2
Technical rules and limits
Rule 1: Development uses multiple signals at once.
Rule 2: Signals act on particular cells in particular places.
Rule 3: Removing one cue can change a specific process.
Where the analogy stops: Signaling networks include feedback and gradients, not a single conductor.
Carry the previous idea forward
True palatal fusion requires removal of the midline epithelial seam so mesenchyme becomes continuous.
Today's technical takeaway
Signals such as SHH, BMP, and FGF carry local instructions that coordinate growth, position, and cell fate.
Now map the same rules onto biology
Map epithelial-mesenchymal cross-talk
Conductor cue
A signaling molecule
Orchestra section
A responding cell population
Musical response
Growth, patterning, or differentiation
Educational illustration, not a clinical photograph. Use the labels and evidence cards to make the biological claim.
Mateo's case file: evidence supplied in this lesson
DEV10-E1
SHH is produced in palatal epithelium and influences nearby mesenchyme.
Why it matters: Signal source and target can be different tissues.
DEV10-E2
BMP and FGF pathways help regulate shelf growth and regional identity.
Why it matters: Several pathways coordinate the process.
DEV10-E3
Changing a pathway in a model can alter proliferation or shape in specific shelf regions.
Why it matters: Signal effects depend on place and time.
Make the clinical decision
You are interpreting a pathway-inhibition experiment.
A drug blocks SHH response only in palatal mesenchyme, and anterior shelf proliferation drops.
AConclude that mesenchymal SHH response supports regional growth in this model.
BConclude that SHH is the only signal in palate development.
CConclude that Mateo received the same drug.
Choose the bounded conclusion and cite source-target and growth evidence.
Evidence required
DEV10-E1 + DEV10-E2 Claim ceiling
You may infer a pathway role in the model and tissue tested. You may not erase other pathways or transfer exposure to Mateo.Go deeper Optional tier 3
Everything required for today is above. Open these only if you want the explainer, source trail, or download files.
The everyday model and Tier 1 check are the complete required path for this lesson.
Use these checks to keep your place. They are not turned in through the portal.
Check off as you finish
- Worked through the everyday picture and answered its three questions.
- Completed the Tier 1 check in plain words.
Turn in: Developmental lesson 10: What Tells Tissues When and Where to Grow: The Signaling Centers SHH, BMP, FGF
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Optional legacy technical materials Open only if you want the original notes, vocabulary, artifact, and CER work
Before this page, you should know
- For the to be one , the on the left and right must become continuous, which requires removing the seam between them.
- Scientists agree the seam disappears, but they have proposed different mechanisms for how its cells leave: EMT, , , and live-.
Today's new idea is only
The shelves grow the right amount in the right place because signaling molecules act as instructions, and removing an instruction gives a too-small or mis-grown shelf, one way a can .
Goal: Explain that palatal shelves grow on schedule because signaling molecules (SHH, BMP, FGF) are released from specific places and act as instructions for when and where grows, and that losing a signal causes a too-small or mis-grown shelf.
Know by the end
- A is a chemical message a cell releases to change nearby cells, and the cells that release it are a .
- In the shelf, the and the carry on constant .
- SHH from the tells the shelf to proliferate; FGF10 from the mesenchyme keeps SHH on, making a ; BMP drives growth especially in the and is dose-sensitive.
- Removing a signal gives a too-small or mis-grown shelf: blocking Hedgehog reception causes complete agenesis, and disrupting FGF gives a poorly grown shelf with wrong-place adhesions.
1
Signals and signaling centers
Model start: Cells cannot see the whole , so they coordinate growth with signaling molecules released from a .
- In the , the surface and the inner carry on a constant -mesenchymal ____ (cross-talk).
- SHH from the tells the to ____ (proliferate); it is the central player in shelf growth.
2
A feedback loop and a dose
- FGF10 from the keeps SHH switched on, making a feedback ____ between the two layers.
- BMP drives growth especially in the ____ ( / front) and is dose-sensitive.
3
Remove a signal, watch the shelf
- Blocking Hedgehog reception gives complete ____ (agenesis / absence) of the secondary .
- A shelf that grows too little cannot reach the to ____, which is one way a can .
Everything you need for today is on this page. These links are optional.
What to read
Read the short plain-language explanation written for this lesson. Plain-language explainer for this lesson
Why this source matters
This explanation gives you the background for today's idea without making you decode a research paper: The shelves grow the right amount in the right place because signaling molecules act as instructions, and removing an instruction gives a too-small or mis-grown shelf, one way a can .
Words to unlock first
signaling moleculesignaling centerSHH (Sonic hedgehog)BMPFGF
Reading moves
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Stop point
Stop after the final 'Use it now' section. The research citations are available separately for advanced readers.
Your output
Write one claim-evidence sentence: state the main idea, then name the example or evidence that supports it.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Developmental domain · Cell communication and growth signals in development
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Build a one-page signal map for Mateo's case file: draw the shelf as two layers (epithelium on the surface, mesenchyme inside) and add three labeled arrows: SHH from epithelium to mesenchyme (grow), FGF10 from mesenchyme back to epithelium (keep SHH on), and BMP in the anterior shelf (front growth, right dose). Add one sentence on how a missing or mis-dosed instruction can leave the shelf too small to reach the midline, and note we cannot read Mateo's embryonic signals from a newborn exam.
Lab / skill
Principles of Biomedical Science (PBS) · Medical Interventions (MI)
Everything required for today's decision is already in the case file and plain-language explainer. The links below are original papers and database records for teachers and advanced readers, not assigned student reading.
- Claim: Palatal shelves grow on schedule because signaling molecules like ____, BMP, and FGF act as instructions.
- Evidence: When the cannot receive the Hedgehog signal, the secondary shows complete ____; when FGF signaling is disrupted, the shelf grows poorly and sticks in the wrong places.
- Reasoning: This matters for Mateo because a shelf that grew too ____ cannot reach the to fuse, adding a molecular possibility to our list that we cannot confirm from a .
How this is graded (rubric)
For: Build a one-page signal map for Mateo's case file: draw the shelf as two layers (epithelium on the surface, mesenchyme inside) and add three labeled arrows: SHH from epithelium to mesenchyme (grow), FGF10 from mesenchyme back to epithelium (keep SHH on), and BMP in the anterior shelf (front growth, right dose). Add one sentence on how a missing or mis-dosed instruction can leave the shelf too small to reach the midline, and note we cannot read Mateo's embryonic signals from a newborn exam.
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in through the route named under Submit here and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "Build a one-page signal map for Mateo's case file: draw the shelf as two layers (epithelium on the surface, mesenchyme inside) and add three labeled arrows: SHH from epithelium to mesenchyme (grow), FGF10 from mesenchyme back to epithelium (keep SHH on), and BMP in the anterior shelf (front growth, right dose). Add one sentence on how a missing or mis-dosed instruction can leave the shelf too small to reach the midline, and note we cannot read Mateo's embryonic signals from a newborn exam.".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be attached to your class form or handed in, and confirmed.
What's next: SHH, BMP, and FGF tell the shelves how much to grow and where, and a missing signal gives a too-small or mis-grown shelf. But growing is not the same as joining: a shelf can grow, elevate, and meet its partner and STILL not fuse. At the last step the two touching shelves must commit to becoming one, and a specific signal flips that switch. What is the master switch for ? We chase that next time.