Clue 1: Orient yourself
Which light shows where the message is?
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
Which test shows where an instruction is used, and which test shows what it does?
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: Orthogonal assays answer different mechanism questions: where RNA or protein is and what changes after perturbation.
On your WebXam
Matching a bench method to the question it answers
For life
Having a gene is not the same as using it.
Principle: Having it is not using it
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
Three flashlights reveal message, material, and system failure
Different flashlights reveal different features of the same object. One can show a message, another the material, and another whether the larger system changed.
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 shows where the working part is?
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
Which reveals what changes when the part is missing?
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 light shows where the message is?
- 2Which shows where the working part is?
- 3Which reveals what changes when the part is missing?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: Which test shows where an instruction is used, and which test shows what it does?
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: Match each assay to one question.
Rule 2: Include negative and positive controls.
Rule 3: Combine location evidence with perturbation evidence before claiming function.
Where the analogy stops: Assays produce measured signals with noise and controls, not perfectly revealing beams.
Carry the previous idea forward
Many tests inflate false positives, so thresholds and independent replication must be planned before results are seen.
Today's technical takeaway
Orthogonal assays answer different mechanism questions: where RNA or protein is and what changes after perturbation.
Now map the same rules onto biology
Test a candidate developmental gene with three assays
Wiring-map light
RNA in situ hybridization
Working-part light
Protein immunohistochemistry
Removal test
Knockout or knockdown phenotype
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
EXP09-E1
RNA signal appears in developing palatal shelves at the relevant stage.
Why it matters: The gene is transcribed in a useful place and time.
EXP09-E2
Protein staining appears in palatal epithelium and is absent in the no-primary-antibody control.
Why it matters: The protein location is supported by a specificity control.
EXP09-E3
Perturbed embryos show altered shelf elevation more often than matched controls.
Why it matters: Changing the gene is associated with a phenotype, but other effects still need checks.
Make the clinical decision
You are planning the bench follow-up to a replicated locus.
The team has funding for three assays and must decide whether one expression image alone proves function.
ACombine RNA location, protein location, perturbation, and controls.
BUse one bright stain as proof the gene causes cleft palate.
CSkip controls because the candidate came from GWAS.
Choose the assay set and state the specific question each assay answers.
Evidence required
EXP09-E1 + EXP09-E2 Claim ceiling
You may connect expression and perturbation evidence. You may not treat location alone as causal proof.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 9: Taking a Gene to the Bench
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 problem appears the moment you test many hypotheses on the same data, because each test gets its own chance to throw a .
- At p < 0.05, running 1,000,000 tests with no real effect yields on average about 50,000 false alarms by chance.
If not, review
Today's new idea is only
A asks if a gene is necessary, in situ asks where it is switched on, and asks where its sits, each read against careful controls.
Goal: Students will describe how a , an , and an experiment each test a different part of a gene's job, and match each method to the question it answers.
Know by the end
- A deletes a gene to see what breaks; a removes it only in chosen cells at a chosen time, so an animal survives long enough to be scored.
- uses a labeled probe to show which cells are transcribing a gene (it detects messenger RNA); uses an to show where a sits.
- Penetrance is the percent of mutants that actually show the phenotype; in the anchor study only about 20 percent of conditional mutants developed a .
- Every staining run needs a (should light up) and a (should stay dark), plus real counting and statistics rather than one cherry-picked image.
1
Three classic moves
Model start: A tests whether a gene is necessary; in situ finds the RNA (where it is switched on); finds the .
- A deletes a gene to see what breaks; many genes are essential, so deleting them everywhere kills the before the forms, which is why we use a that removes the gene only in chosen cells at a chosen time.
- shows which cells are transcribing a gene (it finds the ____, messenger RNA); shows where a ____ () sits.
2
Penetrance
- Penetrance is the percent of mutants that actually show the phenotype; in the anchor study only about ____ percent (20 percent) of conditional mutants developed a .
- So you cannot expect a clean yes on every animal, and partial penetrance is normal in biology rather than a failed experiment.
3
Controls keep it honest
- Every experiment needs a control: a that should light up and a that should not, on every run.
- And you count stained cells with real statistics instead of admiring one cherry-picked image, because a glowing slide alone proves nothing.
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 asks if a gene is necessary, in situ asks where it is switched on, and asks where its sits, each read against careful controls.
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 · Laboratory methods, from association to mechanism
WebXam domain
Molecular and Genetic Technology
Evidence to produce
For each question, name the single best method (knockout, in situ hybridization, or immunohistochemistry) and one control: does removing IRF6 from the palate epithelium stop fusion; which cells switch IRF6 messenger RNA on and when; is the IRF6 protein present in surface periderm cells as the shelves touch. Then explain how you would honestly report a 30 percent penetrance result.
Lab / skill
Biomedical Innovations (BI) · Medical Interventions (MI)
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: A is the right tool to test whether IRF6 is needed for .
- Evidence: In the anchor study, a straight of an essential gene was ____ (lethal) before the palate formed, so the team removed it only in the ____ (palate ).
- Reasoning: A lets the animal ____ (survive) long enough to score the , so we can see whether losing the gene breaks .
How this is graded (rubric)
For: For each question, name the single best method (knockout, in situ hybridization, or immunohistochemistry) and one control: does removing IRF6 from the palate epithelium stop fusion; which cells switch IRF6 messenger RNA on and when; is the IRF6 protein present in surface periderm cells as the shelves touch. Then explain how you would honestly report a 30 percent penetrance result.
| 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 "For each question, name the single best method (knockout, in situ hybridization, or immunohistochemistry) and one control: does removing IRF6 from the palate epithelium stop fusion; which cells switch IRF6 messenger RNA on and when; is the IRF6 protein present in surface periderm cells as the shelves touch. Then explain how you would honestly report a 30 percent penetrance result.".
- 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: A removes a gene and a stain shows where it sits, but both are slow and blunt; building a conditional-knockout mouse takes many crosses and many months. Is there a faster, more precise way to edit a gene on purpose and read out exactly what it does?