Organisms with the genotypes AABbCcDd and AaBbCcDd are crossed. What are the expected proportions of the following progeny?

A–B–C–D–

Verified step by step guidance

1. Identify the genotypes of the parents: AABbCcDd and AaBbCcDd.
2. Determine the possible gametes each parent can produce. For AABbCcDd, consider the combinations of alleles for each gene: A, B or b, C or c, D or d. For AaBbCcDd, consider the combinations of alleles for each gene: A or a, B or b, C or c, D or d.
3. Calculate the probability of each desired genotype in the progeny. For A–B–C–D–, each gene must have at least one dominant allele (A, B, C, D).
4. For each gene, calculate the probability of having at least one dominant allele in the progeny. Multiply these probabilities together to find the overall probability of the A–B–C–D– genotype.
5. Sum the probabilities of all combinations that result in at least one dominant allele for each gene to find the expected proportion of progeny with the A–B–C–D– phenotype.

Key Concepts

Genotype

A genotype refers to the genetic constitution of an organism, specifically the alleles it possesses for a particular gene. In the given question, the genotypes AABbCcDd and AaBbCcDd indicate the combinations of dominant and recessive alleles for four different genes. Understanding how these alleles interact is crucial for predicting the offspring's traits.

Punnett Square

A Punnett square is a diagram used to predict the genotypes of offspring from a genetic cross. It allows for the visualization of how alleles from each parent combine, helping to determine the probabilities of various genotypes and phenotypes in the progeny. This tool is essential for calculating the expected proportions of specific combinations, such as A–B–C–D–.

Independent Assortment

Independent assortment is a principle of genetics stating that alleles for different traits segregate independently of one another during gamete formation. This means that the inheritance of one trait does not affect the inheritance of another. In the context of the question, this principle is vital for understanding how the combinations of alleles from the two parent genotypes will result in various progeny genotypes.