A geneticist from an alien planet that prohibits genetic research...

Question

A geneticist from an alien planet that prohibits genetic research brought with him to Earth two pure-breeding lines of frogs. One line croaks by uttering 'rib-it rib-it' and has purple eyes. The other line croaks more softly by muttering 'knee-deep knee-deep' and has green eyes. With a newfound freedom of inquiry, the geneticist mated the two types of frogs, producing F₁ frogs that were all utterers and had blue eyes. A large F₂ generation then yielded the following ratios:

27/64 blue-eyed, 'rib-it' utterer 
12/64 green-eyed, 'rib-it' utterer 
9/64 blue-eyed, 'knee-deep' mutterer 
9/64 purple-eyed, 'rib-it' utterer 
4/64 green-eyed, 'knee-deep' mutterer 
3/64 purple-eyed, 'knee-deep' mutterer

One set of crosses with his true-breeding lines initially caused the geneticist some confusion. When he crossed true-breeding purple-eyed, 'knee-deep' mutterers with true-breeding green-eyed, 'knee-deep' mutterers, he often got different results. In some matings, all offspring were blue-eyed, 'knee-deep' mutterers, but in other matings all offspring were purple-eyed, 'knee-deep' mutterers. In still a third mating, 1/2 blue-eyed, 'knee-deep' mutterers and 1/2 purple-eyed, 'knee-deep' mutterers were observed. Explain why the results differed.

Accepted Answer

Welcome back. Let's look at our next question. The phenomenon where type of inheritance in which two alleles of the same gene are both expressed in the same degree within an organism is called and our choices are homo hetero zegas excessive or co dominant. And the answer you were looking for is choice D co dominant. We're talking about a situation where both alleles are expressed in the same degree. So you don't have one a little being dominant over the other. So one being sort of masked if you have a recessive gene being masked, if you have a dominant gene present in a situation where genes are co dominant, it means that in the case of heterocyclic, it's who have copies of both alleles rather than one being dominant over the other. Both alleles are expressed simultaneously. So that means say for example, in chickens where you have a co dominant gene for feather color, Hetero sickos, chicken with one a little for black feathers and one for white feathers. Its phenotype will be speckled, will be expressing both the black and white feather color a little simultaneously. There are flowers with co dominant gene for color where they have an alibi for red and an alley for white that are co dominant in those flowers ahead or a zig, it appears pink. The red and white flower color alleles are expressed simultaneously rather than one being dominant over the other. So again, we look quickly at our other answers. Choice a homo zegas that's incorrect. That refers to obviously an organism with two copies of the same. A little choice be hetero hetero ziggy's just means an individual who has two different copies of the audio for the same gene. Um You could be headed for a dominant and recessive gene. That doesn't mean that both are expressed at the same time and then Choice C. Recessive. Um No that would not be this situation where both genes are expressed in the same degree. A recessive gene is expressed to a lesser degree than a dominant gene. So we'll cross that out again. Um The type of inheritance where two allies of the same gene are both expressed in the same degree within an organism is called choice D. Co dominant. Hope to see you in the next video.

Key Concepts

Mendelian Genetics

Genotype and Phenotype

Incomplete Dominance and Codominance

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