Clue 1: Orient yourself
What changes after the part is removed?
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 extra test shows that a missing part caused the problem?
Why it matters: Clinical recommendations affect real children and families. Fair comparisons, bias control, ethical limits, and honest uncertainty keep a promising result from becoming a harmful claim. Today you practice the professional reasoning behind that work: Loss plus targeted rescue strengthens causation when the rescue is specific, verified, and compared with controls.
On your WebXam
Identifying which result completes a causal argument (rescue, sufficiency)
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 circuit part, then restore that same part
Removing one circuit part tests whether a function depends on it. Restoring the same part tests whether the lost function returns for the expected reason.
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 replacement restores function?
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 test a wrong or empty replacement?
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.
- 1What changes after the part is removed?
- 2Which replacement restores function?
- 3Why test a wrong or empty replacement?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: What extra test shows that a missing part caused the problem?
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: Show what changes after one working part is removed.
Rule 2: Restore that working part in the relevant place and time.
Rule 3: Compare the repair with empty and unrelated replacements.
Where the analogy stops: Working parts act together, so a repair can be partial and may follow more than one route.
Carry the previous idea forward
A model earns relevance by matching the mechanism and outcome needed for the question while following Replace, Reduce, and Refine.
Today's technical takeaway
Loss plus targeted rescue strengthens causation when the rescue is specific, verified, and compared with controls.
Now map the same rules onto biology
Test knockout and epithelial rescue of a palate phenotype
Working circuit
Wild-type development
Missing component
Specific loss of gene function
Targeted replacement
Tissue and time-matched rescue
Educational illustration, not a clinical photograph or a patient-specific study plan. Use the supplied evidence cards and claim ceiling.
Mateo's case file: evidence supplied in this lesson
EXP12-E1
Wild-type cultures fuse in 18 of 20 samples, while knockout cultures fuse in 4 of 20.
Why it matters: Loss of function is associated with a large defect in this model.
EXP12-E2
Targeted epithelial rescue restores fusion in 15 of 20 knockout samples.
Why it matters: Restoring function in the relevant tissue recovers much of the outcome.
EXP12-E3
Empty-vector rescue produces fusion in 5 of 20 samples.
Why it matters: The delivery procedure alone does not explain the targeted rescue.
Make the clinical decision
You are the mechanism-review panelist.
The team must decide whether knockout alone is enough for its strongest causal claim.
AUse knockout plus targeted rescue and controls to strengthen the model-specific causal claim.
BClaim the gene is sufficient for normal human palate development from knockout alone.
CIgnore the empty-vector group because rescue improved.
Choose the claim and compare all four supplied groups.
Evidence required
EXP12-E1 + EXP12-E2 Claim ceiling
You may claim that targeted restoration strengthens causation in this model. You may not claim strict sufficiency or a patient-specific cause.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: Experimental Design lesson 12: Knock It Out, Then Put It Back: Proving a Gene Causes a Defect
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
- An is a non-human organism studied to learn about a human condition; it is a stand-in, never the disease itself.
- asks whether the model disrupts the same cause (gene or pathway) believed to act in humans; asks whether the model looks like the human disease.
If not, review
Today's new idea is only
A shows a gene is needed (necessity), but only adding it back and recovering the structure (the rescue, sufficiency) closes the loop from correlation to causation.
Goal: Explain why a alone cannot prove causation, and how adding a rescue (and a ) completes the causal argument.
Know by the end
- A removes a gene to see what fails; by itself it shows the gene is needed but does not prove the gene, and nothing else, caused the defect.
- A deletes a possible backup gene (here Ezh1) to rule out that the backup, not your gene, explains the result; losing Ezh1 alone did nothing to the .
- A re-supplies the missing gene or signal and asks whether the defect disappears; in the example, removing it blocks and adding it back restores fusion.
- plus rescue tests necessity (remove it and it breaks) plus sufficiency or restoration (add it back and it recovers), the gold-standard causal proof in developmental biology.
1
Two controls complete the argument
Model start: By itself a shows the gene is needed for normal development. That is real evidence, but it is not full proof, because the edit might disturb something else, or a hidden backup might be the true actor.
- A deletes a possible ____ gene (here, Ezh1) to show the result is not secretly about that backup.
- A re-supplies the missing gene or signal and asks whether the defect ____ (disappears / worsens).
- If putting it back fixes the , you have linked that exact ____ to the outcome.
2
Necessity and sufficiency
- Necessity: remove it and the structure ____ (the ).
- Sufficiency or restoration: add it back and the structure ____ (the rescue).
- plus rescue beats a mere correlation because the tracks the gene in both directions, ____ and off.
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: A shows a gene is needed (necessity), but only adding it back and recovering the structure (the rescue, sufficiency) closes the loop from correlation to causation.
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 · Experimental Design domain · Causal inference; necessity and sufficiency through knockout-plus-rescue and redundancy controls
WebXam domain
Molecular and Genetic Technology
Evidence to produce
A colleague reports: I knocked out Gene X in the palate and 30% of pups had clefts, so Gene X causes cleft palate. As the causal-inference scientist, design the two experiments that would let them honestly make that claim. (1) Write the rescue experiment in one sentence (what you put back, and what result would support causation). (2) Write the redundancy control in one sentence (what backup you would test, and why). (3) State the one rescue result that would disprove 'Gene X causes the cleft.'
Lab / skill
Biomedical Innovations (BI) · AP Biology
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.
How this is graded (rubric)
For: A colleague reports: I knocked out Gene X in the palate and 30% of pups had clefts, so Gene X causes cleft palate. As the causal-inference scientist, design the two experiments that would let them honestly make that claim. (1) Write the rescue experiment in one sentence (what you put back, and what result would support causation). (2) Write the redundancy control in one sentence (what backup you would test, and why). (3) State the one rescue result that would disprove 'Gene X causes the cleft.'
| 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 colleague reports: I knocked out Gene X in the palate and 30% of pups had clefts, so Gene X causes cleft palate. As the causal-inference scientist, design the two experiments that would let them honestly make that claim. (1) Write the rescue experiment in one sentence (what you put back, and what result would support causation). (2) Write the redundancy control in one sentence (what backup you would test, and why). (3) State the one rescue result that would disprove 'Gene X causes the cleft.'".
- 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: In a mouse we control everything, so we can prove cause by cutting a gene and putting it back. But we cannot assign a gene, or a surgery, to a baby like Mateo on purpose. When the subjects are children and the question is which treatment is better, how do we make a fair comparison without controlling their biology directly? We chase that next time.