Tongue Rolling Ability: Genetic Inquiry
What is an autosomal dominant gene?
An autosomal dominant gene is a type of genetic inheritance pattern in which a single copy of the mutated gene, inherited from either parent, is sufficient to cause the expression of the trait or disorder associated with the gene. This means that individuals who inherit the mutated gene will have the trait or disorder, regardless of whether the other copy of the gene is normal or mutated.
Based on the data, what are the genotypes of Penny, her father, and her mother?
A. Penny: aa Penny's father: Aa Penny's mother: Aa
B. Penny: aa Penny's father: Aa Penny's mother: aa
C. Penny: Aa Penny's father: Aa Penny's mother: Aa
D. Penny: AA Penny's father: aa Penny's mother: Aa
E. Penny: xaxa Penny's father: xAy Penny's mother: xAxa
Final Answer:
Penny's inability to roll her tongue indicates she has a homozygous recessive genotype (aa). Her parents must be heterozygous (Aa) carriers of the dominant trait, as they can both roll their tongues yet have a child who cannot, which makes the correct answer A.
Explanation:
The ability to roll the tongue is an autosomal dominant trait, meaning an individual needs only one copy of the dominant allele to exhibit the trait. Since Penny cannot roll her tongue, her genotype must be homozygous recessive (aa). Her parents, who can both roll their tongues, each have at least one dominant allele. However, since they have produced a child with the recessive phenotype, it indicates that they must be carrying a recessive allele as well. Thus, each parent is heterozygous (Aa).
The correct genotypes are:
- Penny: aa (homozygous recessive)
- Penny's father: Aa (heterozygous)
- Penny's mother: Aa (heterozygous)
Therefore, the answer is A. Penny: aa Penny's father: Aa Penny's mother: Aa.