Taking a Gene to the Bench
Experimental Design domain · Lesson 9 of 20 · Biomedical Innovations (BI)
Today's goal: Students will describe how a knockout, an in situ hybridization, and an immunohistochemistry experiment each test a different part of a gene's job, and match each method to the question it answers.
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.
Method-to-question match for studying IRF6 in palate fusion:
- Does removing IRF6 from the palate epithelium stop fusion? Method: conditional knockout. Control: littermates that keep the gene; expect them to fuse normally.
- Which embryonic cells switch IRF6 messenger RNA on, and when? Method: in situ hybridization. Control: a sense (or no-probe) negative control that should stay dark, and a tissue known to express IRF6 as a positive control.
- Is the IRF6 protein present in surface periderm cells when the shelves touch? Method: immunohistochemistry. Control: a no-primary-antibody negative control that should stay dark, plus a known-positive tissue.
Reporting 30 percent penetrance honestly: state that 30 percent of mutants showed the cleft and 70 percent did not, which is partial penetrance, common in biology and reported openly; it does not mean IRF6 is unimportant, because other modifiers and chance influence whether the phenotype appears.
This model shows the level of evidence and organization needed to complete: A matched plan pairing each research question with the right bench method and a control.
- Identify the purpose, hazards, and required controls.
- Write the procedure in a usable order.
- Confirm materials, measurements, and waste handling before starting.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Note that low penetrance is reported, not hidden, and does not mean the gene is unimportant.
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: Which test shows where an instruction is used, and which test shows what it does?
- 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: For each question, name the single best method (, , or ) and one control: does removing IRF6 from the stop ; which cells switch IRF6 messenger RNA on and when; is the IRF6 present in surface cells as the shelves touch. Then explain how you would honestly report a 30 percent penetrance result.
- 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 through the route named under Submit here 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 "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.
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.
It builds this reusable test skill: Matching a bench method to the question it answers.
- Name the concept or data pattern being tested.
- Cross out choices that violate that rule or the evidence.
- Justify the best remaining choice before checking the answer.