Yeast are single-celled eukaryotic organisms that grow in culture...

Question

Yeast are single-celled eukaryotic organisms that grow in culture as either haploids or diploids. Diploid yeast are generated when two haploid strains fuse together. Seven haploid mutant strains of yeast exhibit similar normal growth habit at 25°C, but at 37°C, they show different growth capabilities. The table below displays the growth pattern

Hypothesize about the nature of the mutation affecting each of these mutant yeast strains, including why strains B and G display different growth habit at C37°C than the other strains.

Accepted Answer

Hello, everyone and welcome to today's video. So a researcher wants to study the inheritance of flower color in a species of plant. They cross a true breeding plant with red flowers with a true breeding plant with white flowers. All of the resulting offspring have pink flowers. The researcher then crosses two of the pink flower offspring together and obtains a ratio of one red, two pink and one white in the next generation. So which of the following statements is true about the inheritance of flower color in this species of plants. As answer choice. A we have flower color is inherited in a dominant recessive pattern with red being dominant and white being recessive as answer choice B, we have flower color is inherited in an incomplete dominance pattern with pink being an intermediate phenotype between red and white. As answer choice C, we have flower color is inherited in a dominant pattern with both red and white. Ali expressed equally in the heterozygous pink offspring. And as an answer choice D we have flower color is inherited in a polygenic pattern with multiple genes contributing to the expression of flower color. So, although this problem is very long, the solution, it can be quite simple. So we have a true breeding plan that is going to be red. And then we have a true breeding plan that is going to be white. Let's say that red is the dominant phenotype and white is going to be a recessive phenotype. So when we mix them together, we obtain all pink floured, meaning that there is some type of mix occurring. Now, let's cancel out this dominant and recessive because if they were in fact dominant and recessive, then mixing them together will obtain us all red flowers. But this is not the case. We have these pink flowers only. So here we really don't have dominant and recessive phenotypes because they have a type of dominance pattern called incomplete dominance where no phenotype is going to be dominant over the other. And when they mix together a type of mix between the two, so red and white will create pink will form eventually. So the correct answer choice here is going to be answer choice. B flower color is inherited in an incomplete dominance pattern. With pink being an intermediate pheno between red and white. I really hope this video helped you and I hope to see you on the next one.

Key Concepts

Haploidy and Diploidy

Temperature Sensitivity in Mutants

Genetic Interaction and Epistasis

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