Clue 1: Orient yourself
How is the intended change confirmed?
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 do scientists make one planned change without trusting a cut in the wrong place?
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: CRISPR is a controlled perturbation only when the edit, mosaicism, phenotype, and off-target controls are verified.
On your WebXam
Identifying the checks that make a CRISPR result trustworthy
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
A precision editor needs verification stations after every change
A precision editor makes one planned change, then checks the target and nearby text. Later checks ask whether the edit still works in the whole document.
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
Where could an unintended edit hide?
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
What if only some copies were changed?
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.
- 1How is the intended change confirmed?
- 2Where could an unintended edit hide?
- 3What if only some copies were changed?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: How do scientists make one planned change without trusting a cut in the wrong place?
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: Sequence the intended target after editing.
Rule 2: Assess mosaicism and plausible off-target sites.
Rule 3: Compare multiple guides, controls, and repeated phenotypes.
Where the analogy stops: Genomes are three-dimensional biological systems, not pages with fully predictable text edits.
Carry the previous idea forward
Orthogonal assays answer different mechanism questions: where RNA or protein is and what changes after perturbation.
Today's technical takeaway
CRISPR is a controlled perturbation only when the edit, mosaicism, phenotype, and off-target controls are verified.
Now map the same rules onto biology
Verify a CRISPR perturbation before reading the palate phenotype
Target word
Guide RNA target sequence
Mixed copies
Mosaic edited and unedited cells
Other pages
Off-target sites
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
EXP10-E1
Sequencing confirms a frameshift in 78 percent of reads from the target tissue.
Why it matters: The edit occurred, but the sample is mosaic.
EXP10-E2
A second guide produces a similar phenotype while a non-targeting guide does not.
Why it matters: Independent perturbation and a negative control strengthen specificity.
EXP10-E3
The top predicted off-target sites show no detectable edits in the supplied assay.
Why it matters: The tested concern is reduced, not eliminated everywhere in the genome.
Make the clinical decision
You are the genome-editing quality reviewer.
One embryo has a palate defect after injection, but the target was not sequenced and no control guide was used.
AWithhold the gene-function claim and require edit plus specificity checks.
BCall the gene causal because CRISPR was injected.
CIgnore mosaicism because some cells were edited.
Choose the claim status and cite the minimum verification steps needed next.
Evidence required
EXP10-E1 + EXP10-E2 Claim ceiling
You may interpret the supplied edit and control checks. You may not claim all off-target effects are absent or a human treatment is ready.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 10: CRISPR as an Experimental Tool
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 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.
If not, review
Today's new idea is only
cuts a chosen DNA site directed by a guide RNA, but speed is not truth, so the result is trusted only after an search and a sequence-verified edit.
Goal: Students will explain how edits a chosen DNA site using a guide RNA, and identify the two checks (sequence-verify the edit, search for cuts) that make a experiment trustworthy.
Know by the end
- is programmable: a guide RNA matches a chosen and directs the Cas9 to cut there, and the cell's repair can be steered to knock a gene out, knock one in, or install a single point .
- To target a new site you only redesign the guide RNA, not rebuild a whole animal, so is far faster than older methods.
- means the guide also cut a near-match site elsewhere; the fix is to search the genome for cuts. Mosaicism means not every cell got edited; the fix is to sequence-verify the edit and report .
- The strongest causal proof is editing plus a rescue: re-add the correct gene and watch the defect disappear.
1
The pieces
Model start: uses a guide RNA to direct Cas9 to cut a chosen DNA site; to retarget it you redesign only the guide RNA.
- is a programmable editing tool: a guide RNA matches a chosen and directs the Cas9 to cut there, after which the cell's repair can knock a gene out, knock one in, or install a single point .
- The power is that to target a new site you only redesign the ____ (guide RNA), not rebuild an entire animal, so it is far faster than older methods.
2
Two checks are mandatory
- means the guide also cut a near-match site elsewhere; the fix is to deliberately search for cuts.
- Mosaicism means not every cell got edited; the fix is to sequence-verify the edit and report the (the percent of alleles actually modified).
3
Rescue closes the loop
- As in Lesson 9, the strongest causal proof is editing plus a ____ (rescue), where you re-add the correct gene and the defect disappears.
- Speed is not the same as truth: a asks is the gene necessary, lets you ask it precisely and fast, and a rescue closes the loop on causation, but every experiment still runs in a model animal, not in Mateo.
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: cuts a chosen DNA site directed by a guide RNA, but speed is not truth, so the result is trusted only after an search and a sequence-verified edit.
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 · Genome editing as an experimental method and its controls
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Write a one-paragraph CRISPR experiment plan to test whether the IRF6 regulatory risk variant can contribute to clefting in a mouse, naming the guide RNA target, the intended edit, one off-target check, one mosaicism (sequence-verification) check, and the rescue step, then explain why the mice clefted so the variant causes clefts is not yet a safe conclusion.
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: is a faster way than a traditional to test what a gene does.
- Evidence: To target a new site you only redesign the ____ (guide RNA), instead of breeding a whole new ____ ( animal).
- Reasoning: But the result is only trustworthy after you check for ____ () cuts and confirm the edit by ____ (), because either problem could cause a misleading phenotype.
How this is graded (rubric)
For: Write a one-paragraph CRISPR experiment plan to test whether the IRF6 regulatory risk variant can contribute to clefting in a mouse, naming the guide RNA target, the intended edit, one off-target check, one mosaicism (sequence-verification) check, and the rescue step, then explain why the mice clefted so the variant causes clefts is not yet a safe conclusion.
| 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 "Write a one-paragraph CRISPR experiment plan to test whether the IRF6 regulatory risk variant can contribute to clefting in a mouse, naming the guide RNA target, the intended edit, one off-target check, one mosaicism (sequence-verification) check, and the rescue step, then explain why the mice clefted so the variant causes clefts is not yet a safe conclusion.".
- 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 can now edit a gene precisely in a mouse, but Mateo is not a mouse. When is a mouse actually a good stand-in for him, and when does the species gap make the answer untrustworthy?