Clue 1: Orient yourself
Which landmark stays with the truck most often?
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 landmark stays with the truck most often?
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: Linkage follows inherited chromosome markers to narrow a gene's address before sequencing names the gene.
On your WebXam
Reading marker co-segregation to localize a gene to a chromosome band
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
Track a delivery truck by the landmarks it passes
A delivery route can be followed by recording landmarks in order. Nearby landmarks narrow the truck's location even when no one watches every mile.
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
What would a route change separate?
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
How close must a landmark be to remain useful?
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 landmark stays with the truck most often?
- 2What would a route change separate?
- 3How close must a landmark be to remain useful?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: Which landmark stays with the truck most often?
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: Track co-inheritance across relatives.
Rule 2: Recombination can separate distant markers.
Rule 3: Strong linkage narrows a region, not one final gene.
Where the analogy stops: Chromosomes recombine biologically; they do not follow roads.
Carry the previous idea forward
Most isolated clefts fit a multifactorial threshold model in which many small influences add to risk.
Today's technical takeaway
Linkage follows inherited chromosome markers to narrow a gene's address before sequencing names the gene.
Now map the same rules onto biology
Follow a linked marker to chromosome 1q32
Truck
Disease-associated chromosome segment
Nearby landmark
DNA marker
Route change
Meiotic recombination
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
GEN04-E1
In large Van der Woude families, certain chromosome 1 markers co-segregated with the phenotype.
Why it matters: The disease locus was linked to that region.
GEN04-E2
Recombination events narrowed the shared interval to 1q32.
Why it matters: Family crossovers set region boundaries.
GEN04-E3
The interval still contained more than one possible gene.
Why it matters: Linkage gives an address range, not a gene name.
Make the clinical decision
You are the linkage analyst for a historical gene hunt.
A marker travels with the syndrome in nearly every informative relative, but several genes lie nearby.
APrioritize the linked interval for sequencing.
BDeclare the marker itself the causal gene.
CIgnore recombination boundaries.
Choose the next step and cite what linkage can and cannot locate.
Evidence required
GEN04-E1 + GEN04-E2 Claim ceiling
You may prioritize a locus. You may not call a marker causal or name IRF6 before sequence evidence.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 4: Hunting the Exemplar Cleft Gene: Linkage to 1q32
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
- Clean autosomal dominant inheritance needs one altered copy of a single gene and shows : an affected person in almost every generation.
- Multifactorial (threshold) inheritance has no single controlling gene; many small genetic and environmental factors add up to a total liability, and a appears only when liability crosses a threshold.
If not, review
Today's new idea is only
You can corner an invisible gene by watching what visible signposts it refuses to let go of.
Goal: Students will use and co-segregation of DNA markers in informative families to narrow an unknown gene to a chromosomal region (1q32), and understand why scientists use clean Mendelian (Van der Woude) families to find a gene that later informs all clefting.
Know by the end
- A is a known, variable spot in the genome used as a trackable signpost; it is not the disease gene itself.
- is the tendency of two spots close together on a to be inherited together.
- Co-segregation is a marker version and a disease being inherited together in every affected family member, and it is the evidence that the gene sits nearby.
- The Van der Woude gene was first localized to band 1q32 by this kind of co-segregation, before anyone knew it was IRF6.
1
Markers and linkage
Model start: A is a trackable signpost, not the disease gene; markers and diseases that pass down together are linked, meaning they sit close together.
- A is a known, variable spot you can track, but it is not the disease gene itself.
- When a marker and a disease pass down together, they show , meaning they sit ____ together on the same .
2
Reading the co-segregation
- Marker M-B on ____ rides with the trait every time, while the chromosome 8 and chromosome 4 markers are shuffled at random.
- So the gene must sit near M-B, in band 1q32; we have found a (a chromosomal address) without yet knowing the gene's name.
3
The honest caveat
- is statistical, not perfect; can occasionally separate a marker from the gene.
- That is why mappers use many families and many markers, not one.
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: You can corner an invisible gene by watching what visible signposts it refuses to let go of.
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 · Unit 2 How to Screen Your Genes, 2.1 Genetic Testing and Screening
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Write the localization line for the case file stating which marker the disease gene co-segregates with and which chromosome band it therefore maps to, circle the two markers you can rule out, and explain why one recombination event would not overturn the conclusion.
Lab / skill
Medical Interventions (MI) · Principles of Biomedical Science (PBS)
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: The exemplar gene is located on ____ at band ____.
- Evidence: In the Van der Woude family, marker ____ (version 7) appears in all ____ affected people and in no unaffected person, while chr 8 and chr 4 markers are mixed.
- Reasoning: Markers that ride with a trait every time are ____ to it, so the gene must sit nearby.
How this is graded (rubric)
For: Write the localization line for the case file stating which marker the disease gene co-segregates with and which chromosome band it therefore maps to, circle the two markers you can rule out, and explain why one recombination event would not overturn the 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 the localization line for the case file stating which marker the disease gene co-segregates with and which chromosome band it therefore maps to, circle the two markers you can rule out, and explain why one recombination event would not overturn the 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 have an address, 1q32, but an address is not a name. What is the actual gene sitting there, and what does it make?