Pedigree clue for a recessive allele?
Reveal answer
Two unaffected parents → affected child.
Key words: unaffected
4(b) INHERITANCE · RECALL
4.24 Family pedigrees
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What is meant by the term pedigree?
Reveal answer
Diagram showing inheritance of a characteristic through a family.
Key words: pedigree
What is meant by the term carrier?
Reveal answer
Heterozygous individual carrying a recessive allele without the recessive phenotype.
Key words: carrier
What is meant by the term proband?
Reveal answer
Individual through whom a family is first identified for investigation.
Key words: proband
Pedigree evidence: for Affected person, give the simple recessive model and the inference.
Reveal answer
Simple recessive model: aa. Inference: Both recessive alleles present.
Key words: Affected person
Pedigree evidence: for Unaffected parent with affected child, give the simple recessive model and the inference.
Reveal answer
Simple recessive model: Usually Aa. Inference: Parent supplied a while showing dominant phenotype.
Key words: Unaffected parent with affected child
Pedigree evidence: for Unaffected person, give the simple recessive model and the inference.
Reveal answer
Simple recessive model: AA or Aa. Inference: Cannot decide without more evidence.
Key words: Unaffected person
Pedigree evidence: for Two unaffected parents, affected child, give the simple recessive model and the inference.
Reveal answer
Simple recessive model: Both carriers. Inference: Supports recessive inheritance.
Key words: Two unaffected parents, affected child
Pedigree evidence: for Two affected recessive parents, give the simple recessive model and the inference.
Reveal answer
Simple recessive model: aa × aa. Inference: All children expected affected.
Key words: Two affected recessive parents
True or false, and why? “Every unshaded person is homozygous dominant.”
Reveal answer
False. In a recessive model, unshaded people may be carriers.
True or false, and why? “A pedigree proves the molecular cause.”
Reveal answer
False. It supports an inheritance pattern; DNA evidence is needed for a specific variant.
True or false, and why? “One small family always identifies the pattern uniquely.”
Reveal answer
False. Several models may fit limited data.
In a family pedigree, what do shaded symbols show?
Reveal answer
People who are affected by (show) the characteristic.
Key words: affected
In a family pedigree, what do circles and squares stand for?
Reveal answer
Circles are females; squares are males.
Key words: females · males
Pedigree clue for a dominant allele?
Reveal answer
Two affected parents → an unaffected child (so both parents are heterozygous).
Key words: affected