A geneticist crosses a pure-breeding strain of peas producing yellow, wrinkled seeds with one that is pure-breeding for green, round seeds

What is the expected phenotype distribution among the F₂ progeny?

Verified step by step guidance

1. <span>Step 1: Identify the genotypes of the parent strains. Pure-breeding strains are homozygous. Assume yellow (Y) is dominant to green (y) and round (R) is dominant to wrinkled (r). Thus, the yellow, wrinkled parent is YYrr and the green, round parent is yyRR.</span>
2. <span>Step 2: Determine the genotype of the F₁ generation by crossing the parent strains. The F₁ generation will be heterozygous for both traits, resulting in YyRr.</span>
3. <span>Step 3: Use a Punnett square to determine the possible genotypes of the F₂ generation. Since there are two traits, a dihybrid cross is needed, which involves a 4x4 Punnett square.</span>
4. <span>Step 4: Calculate the phenotypic ratio of the F₂ generation. The expected phenotypic ratio for a dihybrid cross is 9:3:3:1, where 9 will show both dominant traits, 3 will show one dominant and one recessive trait, another 3 will show the other dominant and recessive trait, and 1 will show both recessive traits.</span>
5. <span>Step 5: Translate the phenotypic ratio into the specific traits: 9 yellow, round; 3 yellow, wrinkled; 3 green, round; 1 green, wrinkled.</span>

Key Concepts

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations, based on the principles established by Gregor Mendel. It involves understanding dominant and recessive alleles, where dominant traits mask the expression of recessive ones. In this case, yellow seeds (dominant) and round seeds (dominant) will influence the phenotype of the offspring.

Phenotype and Genotype

Phenotype refers to the observable characteristics of an organism, such as seed color and shape, while genotype refers to the genetic makeup that determines these traits. The F₂ progeny will exhibit a range of phenotypes based on the combinations of alleles inherited from the parental generation, which can be predicted using a Punnett square.

Punnett Square

A Punnett square is a diagram used to predict the genetic outcomes of a cross between two organisms. By organizing the possible gametes from each parent, it allows for the visualization of potential genotypes and phenotypes in the offspring. In this scenario, it will help determine the expected distribution of yellow, round, green, and wrinkled seeds among the F₂ progeny.