In a species of the cat family, eye color can be gray, blue, gree...

Question

In a species of the cat family, eye color can be gray, blue, green, or brown, and each trait is true breeding. In separate crosses involving homozygous parents, the following data were obtained:

Cross P₁ F₁ F₂
A green x gray all green 3/4 green: 1/4 gray
B green x brown all green 3/4 green: 1/4 brown
C. gray x brown. all green 9/16 green: 3/16 brown
3/16 gray: 1/16 blue

In a cross between a gray-eyed cat and one of unknown genotype and phenotype, the F₁ generation was not observed. However, the F₂ resulted in the same F₂ ratio as in cross C. Determine the genotypes and phenotypes of the unknown P₁ and F₁ cats.

Accepted Answer

Hello, everyone and welcome to today's video. So black between parenthesis, capitalize B and Y between parentheses, capitalize D I s are dominant over blue, lowercase B and narrow, lowercase D I s if the mother has blue and white and then we have the genotype being homozygous recessive for B homozygous dominant for the eyes. And the father has black and narrow, which is heterozygous for B homozygous recessive for the eyes. What is the probability of producing a fully heterozygous for B and D genotype offspring? So as answer choice is A, we have 50% B 25% C 75% D 15%. So first of all, let's analyze the genotype of the parents first. We have the mother, we ha which has a homozygosis and homozygosis dominant for B first and then the genotype and then we have the father which is going to have A he I guess for B any homicide goes recessive for the genotype. So when we're making these crosses, which involve two genes, we're going to be using two pont square for each cross for one gene and then the other gene. So let's introduce these pont squares into the screen right now and here we have them. So in this case, we're going to be, first of all analyzing gene B, which is going to be on top, we're going to put the mother, which is homozygous recessive for B and then at the bottom or at the side, we're going to put the father, which is heteros for B, once we make this cross, we obtain the following. So the question is asking us for which or what is the probability of obtaining a heterozygous B and heterozygous D genotype offspring. So in this case, the probability of obtaining a heterozygous B is going to be 1/2 because we have 2/4 offspring bean heterozygote for B. Now let's move on to the gene V and this is what we have. So once we make this cross, we're going to obtain the following, we're going to obtain that all offspring are going to be heterozygosity. And therefore the probability of obtaining a heterozygous for D offspring is going to be one or just 100%. So all we have to do to obtain the joint probability of obtaining a fully heterozygote for B and the genotype offspring is going to multiply these two probabilities. And the result is going to be 1/2, which is going to be equal to 50%. Looking at our answer choices. The correct answer for this question is going to be A which is 50%. I really hope this video helped you and I hope to see you on the next one.

Key Concepts

Mendelian Genetics

Genotype and Phenotype

Punnett Squares and Ratios

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