Periderm and IRF6, the Non-Stick Coating on the Embryo
Developmental domain · Lesson 13 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Explain that the periderm 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 palate fusion.
What a finished product looks like
This is a model of the work you should turn in. Use it to check your own: match the structure and the level of detail, do not copy it. Your wording should be your own.
Arrow 1 (must NOT stick): points to where the palate shelf passes next to the tongue. The periderm keeps these surfaces apart so the shelf can lift.
Arrow 2 (must fuse): points to where the two shelf edges meet at the midline. Here the periderm peels away on cue so the medial edge layers can join.
The periderm and its gene IRF6 matter because they decide which oral surfaces stay apart and which are allowed to fuse. A too-sticky periderm could cause a cleft even with normal shelf growth: if the shelf glues to the tongue (an intraoral adhesion), it cannot elevate into place, so fusion never gets a chance (PMID:26589921).
How this was built, step by step
The finished product above did not appear all at once. Here is the path from the question to the turned-in work, so you can follow the same steps.
- 1Start from today's question: What keeps the surfaces inside the mouth from sticking to the wrong neighbor, and what happens when that protection is missing?
- 2Work the Model and the Explore questions to reason it out before writing anything.
- 3Pull the specific evidence the product needs from the reading and any database you used.
- 4Write it up in the required format: Annotate a diagram of a 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 and its gene IRF6 matter because they decide ____," then add one line on why a sticky periderm could cause a even though no shelf failed to grow.
- 5Check it against the rubric, then submit.
| 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. |
- 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 turned in on Schoology and confirmed.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.