SNP and PTC case
Mon, Oct 19, 2026 · Week 9 · Genetics of Disease (Medical Interventions)
Today's goal: Connect a single-nucleotide polymorphism to a phenotype using the PTC-tasting genotype dataset.
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
I found the SNP column for the TAS2R38 PTC-tasting gene and matched each person's genotype to their tasting phenotype. I used T for the taster allele and t for the non-taster allele.
Does the tasting allele track with the trait? Yes. Everyone with at least one T allele tasted PTC, and the only non-taster was homozygous tt. Evidence: Person 1 (TT) and Person 2 (Tt) both tasted; Person 3 (tt) did not, so the T allele tracks with tasting and behaves as dominant.
Carrier prediction: Person 2 is a heterozygous taster (Tt). They show the taster phenotype but carry one non-taster allele, so they could pass the non-taster allele to a child.
| Person | Genotype | Zygosity | Phenotype |
|---|---|---|---|
| 1 | TT | homozygous | taster |
| 2 | Tt | heterozygous | taster |
| 3 | tt | homozygous | non-taster |
This model shows the level of evidence and organization needed to complete: Completes the SNP case analysis: a genotype-to-phenotype table for three individuals with homozygous or heterozygous labels, an evidence sentence, and a carrier prediction.
- Name the variables and include units.
- Enter observations without changing the raw values.
- Check labels, calculations, and patterns before interpreting the data.
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: Submit your genotype-to-phenotype table and prediction to Schoology.
Turn in: Genotype-to-phenotype table
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.
Claim ceiling: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
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: Linking a SNP genotype to phenotype and identifying carriers.
- 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.