Pedigree logic
Fri, Oct 16, 2026 · Week 8 · Genetics of Disease (Medical Interventions)
Today's goal: Use pedigree symbols to track an inherited trait and identify carriers across generations.
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 drew the family using standard symbols: squares for males, circles for females, filled-in shapes for affected individuals, and a horizontal line for each mating.
Mode of inheritance: This trait is autosomal recessive.
Evidence from the pattern: In Generation II, two unaffected parents produced an affected daughter. Two unaffected parents can only have an affected child if both are carriers of a recessive allele, so the trait must be recessive (not dominant), and it appears in both sexes, so it is autosomal, not X-linked.
Carriers I circled: Both Generation II parents must be carriers, because each had to pass one recessive allele to their affected child while showing no trait themselves. I circled both. I can explain the father: he is unaffected, so he has at least one working allele, but his affected child received a non-working allele from him, so he must carry one of each.
| Individual | Symbol | Status |
|---|---|---|
| Gen I male | square | unaffected |
| Gen II father | square | carrier (circled) |
| Gen II mother | circle | carrier (circled) |
| Gen III daughter | filled circle | affected |
This model shows the level of evidence and organization needed to complete: Completes the pedigree analysis: a correctly drawn three-generation pedigree with carriers circled, the mode of inheritance stated, and one sentence of evidence from the pattern.
- 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 pedigree and inheritance call to Schoology.
Turn in: Three-generation pedigree with carriers
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 pedigree logic. 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: Determining mode of inheritance from a pedigree pattern.
- 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.