Question

The pedigree below traces the inheritance of alkaptonuria, a biochemical disorder. Affected individuals, indicated here by the colored circles and squares, are unable to metabolize a substance called alkapton, which colors the urine and stains body tissues.

Answer 1

Affected individuals with alkaptonuria have the genotype 'aa,' and unaffected individuals have the genotypes 'AA' or 'Aa.' If an affected child has unaffected parents, the parents are heterozygous 'Aa' carriers.

Step-by-step explanation:

The student's question is regarding the determination of the genotypes of individuals labeled 1, 2, and 3 in a pedigree chart for the inheritance of alkaptonuria, a recessive genetic disorder. Alkaptonuria is a condition where affected individuals cannot properly metabolize two amino acids, phenylalanine and tyrosine, leading to symptoms like darkened skin, brown urine, and joint damage. Based on the information provided, we can infer that affected individuals have the genotype aa, and unaffected individuals have either the genotype AA or Aa. If a child is affected but the parents are not, the parents must be heterozygous (Aa) since they are carriers of the recessive allele. If neither an individual's genotype nor their manifestation of the disorder is known, but they are known to be unaffected, they will be assigned the genotype A? because they must have at least one normal allele.

Answer 2

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