Clue 1: Orient yourself
Why is the protective layer temporary?
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
What keeps the inside of a forming mouth from sticking to the wrong surface?
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: IRF6-dependent periderm acts as a temporary non-stick surface that prevents the wrong oral tissues from adhering.
On your WebXam
Connecting loss of a non-stick coating to a blocked elevation step
For life
When something appears after you remove a signal, look for the brake that was holding it down.
Principle: Held down, not gone
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
Protective film keeps stacked labels from sticking early
Adhesive labels often have a removable film over the sticky side. The film prevents the wrong surfaces from joining before the labels are placed correctly.
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 the sticky surfaces meet too early?
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
When should the protection be removed?
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 is the protective layer temporary?
- 2What happens if the sticky surfaces meet too early?
- 3When should the protection be removed?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: What keeps the inside of a forming mouth from sticking to the wrong surface?
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: A temporary surface layer can prevent wrong contacts.
Rule 2: Differentiation gives a cell layer a specialized function.
Rule 3: Loss of protection can create a mechanical block later.
Where the analogy stops: Periderm is a living epithelial layer with regulated genes, not plastic film.
Carry the previous idea forward
Wnt switches on Twist1, and Twist1 holds down Sox9 so cranial progenitors move away from cartilage and toward dermal and bone fates.
Today's technical takeaway
IRF6-dependent periderm acts as a temporary non-stick surface that prevents the wrong oral tissues from adhering.
Now map the same rules onto biology
Connect IRF6, periderm, and oral adhesion
Protective film
Periderm
Film-making instruction
IRF6-dependent differentiation
Labels stuck too early
Abnormal tongue-palate or oral epithelial adhesion
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
DEV13-E1
Periderm covers embryonic oral epithelial surfaces during key stages.
Why it matters: It provides a temporary specialized surface.
DEV13-E2
Irf6-deficient mouse embryos have abnormal periderm differentiation.
Why it matters: IRF6 is required for normal protection in the model.
DEV13-E3
Abnormal oral adhesions can block palatal shelf elevation.
Why it matters: A surface defect can create a later movement defect.
Make the clinical decision
You are explaining an Irf6 mutant image to a clinical genetics group.
The shelves formed, but one shelf is attached to the tongue before elevation.
ATrace the failure from periderm loss to abnormal adhesion to blocked elevation.
BSay the shelf failed because it never existed.
CCall every IRF6 variant a complete gene knockout.
Choose the causal sequence and cite the surface and movement evidence.
Evidence required
DEV13-E1 + DEV13-E2 Claim ceiling
You may explain the knockout mechanism. You may not treat all human IRF6 variants as identical to a complete mouse knockout.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 13: Periderm and IRF6, the Non-Stick Coating on the Embryo
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
- A single cranial cell can become bone (), skin (dermal fibroblast), or (chondrocyte), choosing at about mouse day E11.5.
- is the : the fate the cell takes when nothing tells it otherwise.
Today's new idea is only
The is a one-cell-thick non-stick coating built by IRF6; without it the oral surfaces glue to the wrong neighbors and block the shelves from lifting.
Goal: Explain that the is a non-stick protective layer made by the gene IRF6, and that losing it lets oral surfaces glue to the wrong neighbors and block .
Know by the end
- The is a single flat layer of cells that wraps embryonic skin and mouth lining and acts as a controlled non-stick coating.
- At true sites the peels away on cue so the layers underneath can join; elsewhere it keeps wrong surfaces apart.
- IRF6 is the gene that builds a working and is the strongest known gene in humans.
- When IRF6 is lost the oral surfaces become sticky, form intraoral adhesions, and physically block the shelves from elevating, giving .
1
A coating with two jobs
Model start: The is a single, flat layer of cells that wraps the outside of embryonic skin and the lining of the mouth.
- It works as a ____ (non-stick) coating: it stops surfaces from gluing to the wrong neighbor.
- At true sites it ____ (peels away / desquamates) so the layers underneath can join.
2
What IRF6 loss does
- When IRF6 is lost, the does not differentiate and the oral surfaces form abnormal ____ (intraoral adhesions).
- Those stuck surfaces physically block the shelves from ____ (elevating / lifting), so the palate cannot fuse.
- IRF6 also acts ____ (cell-autonomously) in bone, so mice without it show poor craniofacial bone and a small jaw.
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 is a one-cell-thick non-stick coating built by IRF6; without it the oral surfaces glue to the wrong neighbors and block the shelves from lifting.
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
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 · PLTW PBS 072110
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Annotate a diagram of a palate shelf rising next to the tongue. Label two arrows: one to a surface that must NOT stick (shelf to tongue) and one to a surface that MUST fuse (shelf edge to shelf edge). Finish: "The periderm and its gene IRF6 matter because they decide ____," then add one line on why a sticky periderm could cause a cleft even though no shelf failed to grow.
Lab / skill
Principles of Biomedical Science (PBS)
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.
- Lan & Jiang 2015, Cellular and Molecular Mechanisms of Palatogenesis (Curr Top Dev Biol)
- Liu et al. 2016, Irf6 directly regulates Klf17 in zebrafish periderm and Klf4 in murine oral epithelium (journal link; use class excerpt if blocked)
- Thompson et al. 2019, A Cleft Lip and Palate Gene, Irf6, in Osteoblast Differentiation of Craniofacial Bone (journal link; use class excerpt if blocked)
- Claim: The is a non-stick coating, and IRF6 is the gene that builds it.
- Evidence: When IRF6 was deleted, the oral surfaces became ____ and formed abnormal ____, which blocked the shelves from ____.
- Reasoning: If losing IRF6 makes the wrong surfaces stick, then IRF6's normal job must be to ____.
How this is graded (rubric)
For: Annotate a diagram of a palate shelf rising next to the tongue. Label two arrows: one to a surface that must NOT stick (shelf to tongue) and one to a surface that MUST fuse (shelf edge to shelf edge). Finish: "The periderm and its gene IRF6 matter because they decide ____," then add one line on why a sticky periderm could cause a cleft even though no shelf failed to grow.
| 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 "Annotate a diagram of a palate shelf rising next to the tongue. Label two arrows: one to a surface that must NOT stick (shelf to tongue) and one to a surface that MUST fuse (shelf edge to shelf edge). Finish: "The periderm and its gene IRF6 matter because they decide ____," then add one line on why a sticky periderm could cause a cleft even though no shelf failed to grow.".
- 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: We now know which surfaces must stay apart and which must fuse, and which gene polices that. But clefts come in different forms: some only the lip, some only the , some both. Which exact step fails for a lip versus a cleft palate?