Kinds of Typos in DNA
Genetics domain · Lesson 7 of 20 · Medical Interventions (MI), with PBS overlap
Today's goal: Students will classify a DNA change as missense, nonsense, frameshift, or splice from a sequence and predict its effect on the protein.
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.
Classification of the three relatives' IRF6 codes:
- Relative A, R84H (amino acid 84, R to H): missense; one amino acid is swapped, so the protein stays full length but may be altered.
- Relative B, R412X: nonsense; codon 412 becomes a stop, so the protein is truncated and the part after position 412 is missing.
- Relative C, a single-base deletion in exon 4: frameshift; one deleted base is not a multiple of three, so every codon downstream is re-grouped wrong, usually ending in an early stop, leaving a truncated, scrambled protein.
Pattern: nonsense and frameshift changes are truncating (least working protein), while missense leaves a full-length protein.
Also due today: Write one classification sentence per relative.
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.
- 1Read the variant code: a letter, a number, a letter (R84C) means one amino acid was swapped.
- 2A letter, a number, then X (R250X) means a stop was inserted at that position.
- 3Classify it: same length with one change is ; an early stop is ; an or deletion not a multiple of three is a ; a change at an intron/exon seam is a .
- 4Predict the : leaves a full-length protein that may still work; and usually destroy most of the protein from that copy.
- 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 "Classify three IRF6 codes (R84H, R412X, and a single-base deletion in exon 4) as missense, nonsense, frameshift, or splice, and for each state whether the protein is likely full-length-but-altered or truncated.".
- 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.