A plant with orange, spotted flowers was grown in the greenhouse from a seed collected in the wild. The plant was self-pollinated and gave rise to the following progeny: 88 orange with spots, 34 yellow with spots, 32 orange with no spots, and 8 yellow with no spots. What can you conclude about the dominance relationships of the alleles responsible for the spotted and unspotted phenotypes? What can you conclude about the genotype of the original plant that had orange, spotted flowers?

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Hi everyone. Let's look at our next problem. A total of 500 100 100 male cats with black coats and long for were made with 100 female cats with the same phenotype Out of these, 500, 281 had black coats and long for 93 had black coats and short for 92 had brown coats and long for and 32 had brown coats and short for if both genes are present on different chromosomes, which one do you believe is the recess of value in each trait studied? Well, since the traits are on different chromosomes, we know they independently assort. We'll start by looking at the ratio of different types of offspring. So I wrote them all down here. And if we divide them all by the smallest number 32, we get a ratio of 8.8 uh Black long, 22.9 black short, 2.9 brown, long to one brown short. Well this looks pretty close to what we'd expect in a di hybrid cross. That would be the case if we had to. Uh the parents were heterocyclic for two different traits. In that case you'd expect to see the offspring and ratio of 9 to 3 to 3 to 1 with nine showing both dominant traits. Three of each type with one dominant one recessive to one with both recessive traits. So when we say if we say that's what we posit that that's what we've got going on here. Then we would say the first one black long is showing two dominant traits. So that's going to lead us to the hypothesis that black is the dominant color fur coat with lower case B. Brown being recessive and that long is the dominant coat length with little L the recessive short coat trait. Well, to kind of confirm my hypothesis, this would be the ratio we expect looking at the two different traits if we want to look at one trade at a time. So let's look at Black vs Brown. So if we look at the ratio of black to brown offspring while black offspring, we get 324 Brown offspring, we have 124. And that's giving us a ratio black to brown Of approximately 3 - one. And that is what we'd expect if we had hetero hetero side across which again we know that both parents had the same phenotype and we'd see A ratio of 3- brown. I'm gonna highlight brown or black. I'm sorry, I'll highlight the black, dominant phenotype too brown and same thing. If we look at the number of different color here, I'll do it in red. If we look at the number with long coats versus the number with short coats, I get a ratio of 125 coats, 125 with short coats so long to short. I also have a ratio of approximately 3-1. And again, if this was a hetero versus heterosexual cross, I would expect that ratio of three for the dominant trait to one with the recessive trait. So that confirms our hypothesis of long being dominant and short being recessive. So our question going back to original question said Which one do you believe is the recessive allele in each trait studied. So we posited that the brown coat is recessive and short for as recessive. So let's look at our answers and we see that choice D. Is brown coat and short for. So that will be our answer here. See you in the next video.

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Key Concepts

Mendelian Genetics

Phenotype and Genotype

Punnett Square