3. Extensions to Mendelian Inheritance

Understanding Independent Assortment

Open Question
A male and a female are each heterozygous for both cystic fibrosis (CF) and phenylketonuria (PKU). Both conditions are autosomal recessive, and they assort independently.

What proportion of the children will have either PKU or CF but not both?
Open Question
A woman expressing a dominant phenotype is heterozygous (Dd) for the gene.

What is the probability that the dominant allele carried by the woman will be inherited by a grandchild?
Open Question
Three independently assorting genes (A, B, and C) are known to control the following biochemical pathway that provides the basis for flower color in a hypothetical plant: Three homozygous recessive mutations are also known, each of which interrupts a different one of these steps. Determine the phenotypic results in the F₁ and F₂ generations resulting from the P₁ crosses of true-breeding plants listed here:colorless(aaBBCC) × green(AABBcc)
Open Question
Three independently assorting genes (A, B, and C) are known to control the following biochemical pathway that provides the basis for flower color in a hypothetical plant: Three homozygous recessive mutations are also known, each of which interrupts a different one of these steps. Determine the phenotypic results in the F₁ and F₂ generations resulting from the P₁ crosses of true-breeding plants listed here:yellow(AAbbCC) × green(AABBcc)
Open Question
Three independently assorting genes (A, B, and C) are known to control the following biochemical pathway that provides the basis for flower color in a hypothetical plant: Three homozygous recessive mutations are also known, each of which interrupts a different one of these steps. Determine the phenotypic results in the F₁ and F₂ generations resulting from the P₁ crosses of true-breeding plants listed here:speckled(AABBCC) × yellow(AAbbCC)
Open Question
An organism having the genotype AaBbCcDdEe is self-fertilized. Assuming the five genes assort independently, determine the following proportions:

progeny that are expected to have a genotype identical to that of the parent
Open Question
An organism having the genotype AaBbCcDdEe is self-fertilized. Assuming the five genes assort independently, determine the following proportions:

gametes that are expected to carry only dominant alleles
Open Question
An organism having the genotype AaBbCcDdEe is self-fertilized. Assuming the five genes assort independently, determine the following proportions:

progeny that are expected to have the genotype AabbCcDdE–
Open Question
An organism having the genotype AaBbCcDdEe is self-fertilized. Assuming the five genes assort independently, determine the following proportions:

gametes that are expected to be ABcde
Open Question
An organism having the genotype AaBbCcDdEe is self-fertilized. Assuming the five genes assort independently, determine the following proportions:

progeny that are expected to have a phenotype identical to that of the parent