Rough draft.This research track is under review with Dr. Atit's lab. Content and sequence may still change.
The Baby Mateo Case
Developmental domainPrinciples of Biomedical Science (PBS)Lesson 11 of 20Your seat: Molecular embryologist
TGF-beta3, the Fusion Switch in the Medial Edge Epithelium
Discovery question
What is the master switch that lets two shelves fuse into one roof, and what happens if it never turns on?
💡 does not build the shelves; it licenses the edge cells to stick and dissolve the seam, so without it the shelves grow, elevate, and touch but never fuse.
The plan
Prerequisite check
Before this page, you should know
- 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 .
Today's new idea is only
does not build the shelves; it licenses the edge cells to stick and dissolve the seam, so without it the shelves grow, elevate, and touch but never fuse.
Learn first
What you will learn
Goal: Explain that turns on in the medial edge and is required for the shelves to stick and dissolve the seam, and predict the that results when it is missing.
Know by the end
- is a that acts as the switch for the , not a growth or movement gene.
- It turns on only in the , the thin strip of cells that will touch the opposite shelf, by about mouse day E13, right before contact.
- A deletes one gene so we can read its job from what breaks.
- In the the shelves grow, elevate, and touch normally but cannot fuse, so the seam stays and the result is .
Learn first
Model: The knockout experiment (mouse data)
A mouse has one chosen gene deleted, so we can see that gene's exact job. Researchers made -knockout embryos and watched their palates develop.
The shelves GREW to normal size. The shelves ELEVATED to above the tongue, on schedule. The shelves MET at the and touched. But the shelves did NOT stick. The midline seam never dissolved, so the stayed open: palate. Even when scientists pushed two shelves into direct contact in a dish, they adhered poorly or not at all (PMID:26589921).
For comparison, in normal mouse embryos is silent during early shelf growth and then switches ON, but only in the MEE strip, by about embryonic day 13, just before the shelves meet (DATA_TABLES.md Table a).
Do the work
Explore (work the model before reading on)
- In which exact cells does turn on, and at what point in the timeline?
- List the steps that worked normally in the , and the one step that failed.
- The shelves grew, elevated, and touched, so the missing gene is NOT a growth gene or a movement gene. What one job does appear to control?
- Why does it make sense that turns on ONLY in the edge cells that touch, and only right before contact, instead of everywhere all the time?
- Predict: imagine a baby whose works fine in the lip region but fails only in the back . What would their look like, and why?
The plan
Guided notes
1
What TGF-beta3 does
Model start: is a that acts as the switch. It does not build the shelves; the shelves can grow and move without it.
- What it gives the edge cells is , the ability to ____ (stick) to the opposite shelf and then ____ (dissolve) the seam.
- It turns on in the by about mouse day ____ (E13), right before the shelves meet.
2
Reading the knockout
- A removes one gene so we can read its job from what ____ (breaks).
- In the , growth, elevation, and contact are all ____ (normal), but the shelves cannot ____ (fuse).
- , works through Smad2/3 with Smad4 and switches on partner genes including ____ (IRF6) that help break down the seam.
Explore
Reading the Research
What to read
Read the title and the abstract only, not the whole paper. Lan & Jiang 2015, Cellular and Molecular Mechanisms of Palatogenesis (Curr Top Dev Biol)
Why this source matters
This is the published evidence behind today's idea: does not build the shelves; it licenses the edge cells to stick and dissolve the seam, so without it the shelves grow, elevate, and touch but never fuse.
Words to unlock first
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
You do not need the methods or statistics yet. If a sentence is about lab technique or math you have not learned, mark it and skip it.
Your output
Write one claim-evidence sentence: what this source claims, and the one piece of evidence that backs it up.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Developmental domain · PLTW PBS 072110
WebXam domain
Bio-Molecular Technology
Evidence to produce
A junior scientist writes: "Mateo's cleft must mean his palate shelves never grew." Write two sentences correcting this. Name at least one OTHER step besides growth that could fail and still leave an open palate, and cite TGF-beta3 as your evidence for why growth alone is not the whole story.
Lab / skill
Principles of Biomedical Science (PBS)
The plan
Track your progress today
Check these off as you work through the lesson, then submit. This tells Mr. Mendoza how you're doing so he can help the class. It does not replace turning in your producible.
Use the code Mr. Mendoza gave you, not your name. Saved on this device.
Check off as you finish
- Read the Model and answered the Explore questions.
- Filled in the guided notes in my own words.
- Defined the new vocabulary with an example.
- Built the producible: A junior scientist writes: "Mateo's cleft must mean his palate shelves never grew." Write two sentences correcting this. Name at least one OTHER step besides growth that could fail and still leave an open palate, and cite TGF-beta3 as your evidence for why growth alone is not the whole story.
- Wrote my Claim, Evidence, and Reasoning exit ticket.
Pick your period and code first.
Check yourself
Exit ticket (Claim, Evidence, Reasoning)
- Claim: is the switch that controls , not palate growth.
- Evidence: In the , the shelves ____ but did not ____.
- Reasoning: Because the only broken step was ____, the missing gene's job must be ____.
How this is graded (rubric)
For: A junior scientist writes: "Mateo's cleft must mean his palate shelves never grew." Write two sentences correcting this. Name at least one OTHER step besides growth that could fail and still leave an open palate, and cite TGF-beta3 as your evidence for why growth alone is not the whole story.
| 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 the right way (Schoology for routine work) 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 "A junior scientist writes: "Mateo's cleft must mean his palate shelves never grew." Write two sentences correcting this. Name at least one OTHER step besides growth that could fail and still leave an open palate, and cite TGF-beta3 as your evidence for why growth alone is not the whole story.".
- 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 turned in on Schoology and confirmed.
Explore
Where this leads: careers
Developmental biologist Molecular embryologist
What's next: We found the switch that tells edge cells to fuse. But before any cell can be an edge cell, it first had to BECOME a particular kind of cell. How does a face cell decide whether to be bone, skin, or in the first place?
What Tells Tissues When and Where to Grow: The Signaling Centers SHH, BMP, FGFThe Wnt/beta-catenin Master Switch, How a Face Cell Decides What NOT to Be