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


AabbCcDd

Verified step by step guidance

1. Determine the genotypes of the parents: The first parent has the genotype AABbCcDd, and the second parent has the genotype AaBbCcDd. Each gene is inherited independently, so we will analyze each gene separately using the rules of Mendelian inheritance.
2. For the 'A' gene: The first parent is homozygous dominant (AA), and the second parent is heterozygous (Aa). Use a Punnett square to determine the offspring's genotypes. The possible outcomes are 50% AA and 50% Aa.
3. For the 'B' gene: Both parents are heterozygous (Bb). Use a Punnett square to determine the offspring's genotypes. The possible outcomes are 25% BB, 50% Bb, and 25% bb. We are specifically interested in the 'bb' genotype, which occurs with a probability of 25%.
4. For the 'C' gene: Both parents are heterozygous (Cc). Use a Punnett square to determine the offspring's genotypes. The possible outcomes are 25% CC, 50% Cc, and 25% cc. We are specifically interested in the 'Cc' genotype, which occurs with a probability of 50%.
5. For the 'D' gene: Both parents are heterozygous (Dd). Use a Punnett square to determine the offspring's genotypes. The possible outcomes are 25% DD, 50% Dd, and 25% dd. We are specifically interested in the 'Dd' genotype, which occurs with a probability of 50%. Multiply the probabilities for each gene (A = Aa, B = bb, C = Cc, D = Dd) to calculate the overall proportion of progeny with the genotype AabbCcDd.

Key Concepts

Genotype

A genotype is the genetic constitution of an organism, represented by the alleles it possesses for a particular gene. In this case, the genotypes AABbCcDd and AaBbCcDd indicate the specific alleles for four different genes. Understanding how these alleles combine during reproduction is crucial for predicting the offspring's genotypes.

Punnett Square

A Punnett square is a diagram used to predict the genetic outcomes of a cross between two organisms. It allows for the visualization of how alleles from each parent combine to form the genotypes of the offspring. By filling out a Punnett square for the given genotypes, one can determine the expected proportions of various progeny genotypes, including AabbCcDd.

Mendelian Inheritance

Mendelian inheritance refers to the patterns of inheritance first described by Gregor Mendel, which include concepts such as dominance, segregation, and independent assortment. These principles explain how alleles are passed from parents to offspring and how they interact to produce different phenotypes. Understanding these principles is essential for calculating the expected proportions of progeny in genetic crosses.