Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:

27/64 brown : 16/64 albino : 9/64 yellow : 9/64 black : 3/64 cream

Verified step by step guidance

1. <span>Step 1: Identify the phenotypic ratio of the progeny. The given ratio is 27:16:9:9:3 for brown, albino, yellow, black, and cream, respectively.</span>
2. <span>Step 2: Recognize that these ratios suggest a dihybrid cross involving two genes, each with two alleles. The phenotypic ratio of 27:16:9:9:3 is a modification of the typical 9:3:3:1 ratio seen in dihybrid crosses.</span>
3. <span>Step 3: Assume that the two genes involved are A and B, where A and B are dominant alleles, and a and b are recessive alleles. The albino phenotype (16/64) suggests a recessive epistasis, where the presence of two recessive alleles (aa) masks the expression of the other gene.</span>
4. <span>Step 4: Determine the genotypes that correspond to each phenotype. For example, brown could be A-B-, albino could be aa--, yellow could be A-bb, black could be aaB-, and cream could be aabb.</span>
5. <span>Step 5: Use the phenotypic ratios to deduce the genotypes of the parents. The presence of all phenotypes suggests that the parents are heterozygous for both genes, likely AaBb x AaBb.</span>

Key Concepts

Genotype

Genotype refers to the genetic constitution of an organism, specifically the alleles it possesses for a particular trait. In this context, understanding the genotype is crucial for predicting the phenotypic ratios of the progeny. The genotype can be homozygous (two identical alleles) or heterozygous (two different alleles), and it directly influences the observable traits in the offspring.

Phenotype

Phenotype is the observable physical or biochemical characteristics of an organism, determined by both its genotype and environmental factors. In the given question, the phenotypic ratios of the progeny (brown, albino, yellow, black, and cream) provide essential clues to deduce the parental genotypes. Understanding how different genotypes manifest as distinct phenotypes is key to solving the problem.

Punnett Square

A Punnett Square is a diagram used to predict the genetic outcomes of a cross between two organisms. It helps visualize the possible combinations of alleles from the parents and the resulting genotypes and phenotypes of the offspring. Utilizing a Punnett Square can clarify how the observed ratios of progeny relate to the genotypes of the parents, making it a valuable tool in genetic analysis.