In rabbits, chocolate-colored fur (w⁺) is dominant to wh...

Question

In rabbits, chocolate-colored fur (w⁺) is dominant to white fur (w), straight fur (c⁺) is dominant to curly fur (c), and long ear (s⁺) is dominant to short ear (s). The cross of a trihybrid rabbit with straight, chocolate-colored fur and long ears to a rabbit that has white, curly fur and short ears produces the following results:

Phenotype Number
White, short, straight 13
Chocolate, long, straight 165
Chocolate, long, curly 13
White, long, straight 82
Chocolate, short, straight 436
Chocolate, short, curly 79
White, short, curly 162
White, long, curly 450
1400

Calculate the recombination frequencies between each of the adjacent pairs of genes.

Accepted Answer

Hey, everyone. Let's take a look at this question together in a tri hybrid cross experiment. A researcher wanted to determine the recombination frequency between three genes and fruit flies, body color, eye color and wing size. The dominant alleles for these genes are black, body color, red, eye color and normal wing size respectively. The recessive alleles are gray body, white, eye color and miniature wing size respectively. The researcher crossed a tri hybrid fly that was heterozygous for all three genes with a fly that was homozygous recessive for all three genes. The resulting f one generation had black body color, red eye color and normal wing size. The researcher then performed a series of test crosses between the f one generation and the homozygous recessive fly for each gene separately in terms of body color and eye color. The results are shown below black body color and white eye color. 20 gray body color and red eye color. 30 black body color and red eye color. 45 gray body color and white eye color. 55. What is the recombination frequency between the body color gene and the eye color gene? Is it answer choice a 45% answer choice. B 50% answer choice C 33% or answer choice D 15%. Let's work this problem out together to try to figure out which of the following answer choices represents the recombination frequency between body color and eye color genes. Though we know that the offspring with the parental alleles are the ones with black body color and red eye color as well as gray body color and white eye color. So these are the parents. And then we know that our recombinant are the ones with black body color and white eye color as well as gray body color and red eye color. And we also know that we calculate the recombination frequency R R F for short by taking the number of competence divided by the total number of offspring and multiplying that by 100 that and we know that the number of recombinant is equal to 50 and the total offspring Is equal to 150. So our recombination frequency is calculated as 50, divided by 150, multiplied by 100% which 50, divided by 150 And be simplified to one, divided by three, multiplied by 100%, which equals 33% since one divided by three is 0.33. And when we multiply that by the 100% we end up with 33% as our recombination frequency, which means that answer choice. C 33% is the correct answer. Since we know that the offspring that are recombinant are black body color and white eye color, as well as gray body color and red eye color, which make up a total of 50 for the number of recombinant. And our total offspring is 150. Though the recombination frequency is calculated as the number of recombinant which is equal to 50 divided by the total offspring, which is equal to 150. And we end up with one divided by three, multiplied by 100% which one divided by three gives us 0.33 And then multiplied by 100%, gives us that final answer of 33%, which is answer choice. C the correct answer. I hope you found this video to be helpful. Thank you and goodbye.

Key Concepts

Dominance and Alleles

Phenotypic Ratios

Recombination Frequency

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