Hunting the Exemplar Cleft Gene: Linkage to 1q32
Genetics domain · Lesson 4 of 20 · Medical Interventions (MI), with PBS overlap
Today's goal: Students will use linkage 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 cleft gene that later informs all clefting.
What a finished product looks like
This is a model of the work you should turn in. Use it to check your own: match the structure and the level of detail, do not copy it. Your wording should be your own.
Localization line: The disease gene co-segregates with marker M-B (version 7) and therefore maps to chromosome band 1q32.
Markers ruled out:
- M-A (chromosome 8): affected people carry mixed versions, so the gene is not there.
- M-C (chromosome 4): affected people carry mixed versions, so the gene is not there.
Why one recombination would not overturn it: a single rare chromosome swap in one cousin could separate the marker from the gene in that one person, but the marker rides with the trait in every other affected member, which is why mappers use many families rather than one.
Also due today: Circle M-A and M-C as the two markers ruled out.
How this was built, step by step
The finished product above did not appear all at once. Here is the path from the question to the turned-in work, so you can follow the same steps.
- 1Start from today's question: How do you hunt a gene when you have no address for it?
- 2Work the Model and the Explore questions to reason it out before writing anything.
- 3Pull the specific evidence the product needs from the reading and any database you used.
- 4Write it up in the required format: Write the localization line for the case file stating which marker the disease gene co-segregates with and which band it therefore maps to, circle the two markers you can rule out, and explain why one event would not overturn the conclusion.
- 5Check it against the rubric, then submit.
| 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 the right way (Schoology for routine work) and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
- 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 turned in on Schoology and confirmed.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.