In tomatoes, the allele T for tall plant height is dominant to dwarf allele t, the P allele for smooth skin is dominant to the p allele for peach fuzz skin, and the allele R for round fruit is dominant to the recessive r allele for oblong fruit. The genes controlling these traits are linked on chromosome 1 in the tomato genome, and the genes are arranged in the order and with the recombination frequencies shown.
A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?

Question

In tomatoes, the allele T for tall plant height is dominant to dwarf allele t, the P allele for smooth skin is dominant to the p allele for peach fuzz skin, and the allele R for round fruit is dominant to the recessive r allele for oblong fruit. The genes controlling these traits are linked on chromosome 1 in the tomato genome, and the genes are arranged in the order and with the recombination frequencies shown.

A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?

Gene arrangement and recombination frequencies for T, P, and R alleles in tomatoes.

A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?

Accepted Answer

Hey, everyone. Let's take a look at this question together in a tri hybrid cross an individual with the genotype heterozygous A heterozygous B and heterozygous C is crossed with another individual with the genotype homozygous recessive A heterozygous B and heterozygous C. The F one generation can have eight different genotypes. Heterozygous A heterozygous B. Heterozygous C, heterozygous A heterozygous B. Homozygous recessive C heterozygous A heterozygous B. Homozygous recessive C, heterozygous A homozygous recessive B. Heterozygous C homozygous recessive A heterozygous B, heterozygous C, homozygous recessive A heterozygous B. Homozygous recessive C homozygous recessive A heterozygous B homozygous recessive C and lastly, homozygous, recessive A homozygous recessive B and heterozygous C. What is the probability of each genotype occurring? Is it answer choice? A one out of two answer choice, B one out of four answer choice C one out of three or answer choice D one out of eight. Let's work this problem out together to try to figure out which of the following answer choices is the probability of each genotype occurring. So we want to figure out the probability of the genotype heterozygous A heterozygous B and heterozygous C occurring, which we know that this. Utilizes the product rule where we have the probability of each gene occurring multiplied by each other. So the probability is equal to the probability of that heterozygous a multiplied by the probability of that heterozygous B multiplied by the probability of the heterozygous C. And so we can set up three puit squares for each gene to get the probability of the heterozygous genotype for each individual gene. And then multiply the probabilities together to get at the total overall probability for the genotype. So starting off with the probability for the allele A, we know we are crossing that heterozygous A with the homozygous recessive A. So we have our heterozygous A on the top of our opponent square and the homozygous recessive A on the left side of our opponent square. And we go ahead and do our cross for the genotypes, which we can see that the probability of that heterozygous genotype is two out of four, which means that the probability of that heterozygous A is one out of two when simplified. And then for B, we are crossing the Heterozygous B with another heterozygous B, we have one heterozygous B on the top of our opponent square and the other on the left side. And we cross the two genotypes and we end up with one homozygous dominant, two heterozygous and one homozygous recessive. And we want to know the probability of that heterozygous which is two out of four. So the probability can be simplified to one out of two. And lastly, we are crossing those two heterozygous genotypes or C which yields the same result as the cross or B. So we have two out of four heterozygous which can be simplified 21 out of two. So we have the probability of heterozygous A is one out of two. The probability of heterozygous B is one out of two. And the probability of that heterozygous C is also one out of two. So we multiply one out of two by one out of two, multiplied by one out of two. And we end up with one out of eight as the pro probability of each genotype occurring, which means that answer choice D one out of eight is the correct answer. Since the probability of each genotype occurring can be calculated by using the product rule in which we multiply the probability of each gene by each other to get that total genotype probability. And the probability of heterozygous A is one out of two. The probability of heterozygous B is also one out of two. And the probability of heterozygous C is one out of two. So we multiply one out of two by one out of two by one out of two to get that total genotype probability of one out of eight, which is answer choice D I hope you found this video to be helpful. Thank you and goodbye.

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Key Concepts

Dominant and Recessive Alleles

Linkage and Recombination

Gamete Formation