Clue 1: Orient yourself
Which comparison shows necessity?
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 can scientists show that one changed instruction caused a problem instead of just being there too?
Why it matters: Genetic results can change family counseling and research decisions. They must be interpreted without turning risk into destiny or an uncertain variant into a diagnosis. Today you practice the professional reasoning behind that work: Knockout and rescue experiments strengthen causation when loss creates a defect and restoration reverses part of it.
On your WebXam
Distinguishing correlation from causation using knockout and rescue logic
For life
To find the cause, change one thing and watch what changes.
Principle: Same look, different cause
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
Remove one bridge cable, then restore it
A bridge cable carries a defined part of the load. Removing it tests what depends on that cable, and restoring it tests whether the same support can recover the function.
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
Which comparison tests sufficiency or rescue?
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
Why might a partial rescue still teach mechanism?
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.
- 1Which comparison shows necessity?
- 2Which comparison tests sufficiency or rescue?
- 3Why might a partial rescue still teach mechanism?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: How can scientists show that one changed instruction caused a problem instead of just being there too?
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: Compare matched control and knockout groups.
Rule 2: Restore the suspected function in a defined tissue or time.
Rule 3: Measure both rescue and remaining defects.
Where the analogy stops: Genes act in networks and tissues, so restoration can be incomplete.
Carry the previous idea forward
The IRF6 network helps oral epithelial cells form periderm, preventing wrong adhesions before correct fusion.
Today's technical takeaway
Knockout and rescue experiments strengthen causation when loss creates a defect and restoration reverses part of it.
Now map the same rules onto biology
Read IRF6 knockout and partial-rescue evidence
Intact bridge
Wild-type control
Cable removed
Irf6 knockout
Cable restored
Tissue-specific or mRNA rescue
Educational illustration, not a clinical photograph or diagnostic result. Use the labeled evidence cards and claim ceiling.
Mateo's case file: evidence supplied in this lesson
GEN15-E1
Irf6 knockout models develop abnormal epithelium, oral adhesions, and cleft palate.
Why it matters: Loss of function produces the predicted phenotype.
GEN15-E2
Restoring epithelial IRF6 reduces some adhesions but does not fully rescue every defect.
Why it matters: The rescue supports an epithelial role and reveals limits.
GEN15-E3
Zebrafish rescue experiments add evidence in a second model.
Why it matters: Cross-model replication strengthens the mechanism while remaining preclinical.
Make the clinical decision
You are judging whether the rescue proves complete correction.
The rescue group has fewer adhesions but still has cleft palate in several regions.
ACall it a partial mechanistic rescue.
BCall it a complete cure.
CIgnore the improvement because it was incomplete.
Choose the verdict and cite both improvement and remaining phenotype.
Evidence required
GEN15-E1 + GEN15-E2 Claim ceiling
You may support causation and a tissue role. You may not claim complete rescue or human treatment.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: Genetics lesson 15: How Do We Prove the Gene Causes It?
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
- The is the sheet of cells covering surfaces; its outermost layer is the , a non-stick protective coating.
- is a cell maturing into a specialized type that does a specific job.
If not, review
Today's new idea is only
When removing a gene breaks the process AND restoring it fixes the process, the gene is a cause, not a bystander; this is how the field proved IRF6 loss causes clefting.
Goal: Use the logic of model-organism knockouts and rescue experiments to argue that IRF6 loss causes clefting rather than merely correlating with it.
Know by the end
- A is an animal studied to learn about a human process; mice and zebrafish are the workhorses for clefting.
- A is an animal with a chosen gene deliberately switched off, compared against a normal wild-type animal.
- Correlation means two things happen together; causation means one actually makes the other happen.
- A puts the gene back: if removing X breaks the process and restoring X fixes it, X is a cause.
1
The trap and the two-step proof
Model start: Seeing a variant alongside a in patients is correlation: two things happen together. To get to causation, that one actually makes the other happen, you need the experiment.
- Step one, : remove IRF6, and the ____ in both mouse and zebrafish.
- Step two, rescue: put IRF6 back, and the is ____ (fully in fish, partly in mouse).
- When removing a gene breaks the process AND restoring it fixes the process, the gene is a ____.
2
Why cross-species matters
- Matching the result in two distant species (mouse and ____) is stronger than one species alone.
- The partial mouse rescue, where the stayed because IRF6 was missing from the , ____ (strengthens / weakens) the claim that IRF6 acts in the periderm.
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: When removing a gene breaks the process AND restoring it fixes the process, the gene is a cause, not a bystander; this is how the field proved IRF6 loss causes clefting.
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 · Genetics domain · Experimental evidence and causation
WebXam domain
Molecular and Genetic Technology
Evidence to produce
A classmate argues: "Mateo has an IRF6 variant and a cleft, so IRF6 must cause his cleft." As the model researcher, write a two-part reply: (1) name what is missing from that argument (correlation vs causation), and (2) describe the knockout-then-rescue experiment in an animal that would actually test it.
Lab / skill
Medical Interventions (MI) · Biomedical Innovations (BI)
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: Losing IRF6 causes clefting (agree or disagree).
- Evidence: In the , removing IRF6 made the ____ in mouse and fish; in the rescue, restoring IRF6 ____ the cleft.
- Reasoning: The remove-then-restore logic proves cause and not just correlation, because ____.
How this is graded (rubric)
For: A classmate argues: "Mateo has an IRF6 variant and a cleft, so IRF6 must cause his cleft." As the model researcher, write a two-part reply: (1) name what is missing from that argument (correlation vs causation), and (2) describe the knockout-then-rescue experiment in an animal that would actually test it.
| 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 "A classmate argues: "Mateo has an IRF6 variant and a cleft, so IRF6 must cause his cleft." As the model researcher, write a two-part reply: (1) name what is missing from that argument (correlation vs causation), and (2) describe the knockout-then-rescue experiment in an animal that would actually test it.".
- 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 proved IRF6 loss causes clefting using and rescue in mouse and zebrafish, so we now understand how the happens in one . But why is cleft lip and far more common in some human populations than in others? We chase that next, when the population geneticist takes the seat.