The boss in your laboratory has just heard of a proposal...

Question

The boss in your laboratory has just heard of a proposal by another laboratory that genes for eye color and the length of body bristles may be linked in Drosophila. Your lab has numerous pure-breeding stocks of Drosophila that could be used to verify or refute genetic linkage. In Drosophila, red eyes (c⁺) are dominant to brown eyes (c) and long bristles (d⁺) are dominant to short bristles (d). Your lab boss asks you to design an experiment to test the genetic linkage of eye color and bristle-length genes, and to begin by crossing a pure-breeding line homozygous for red eyes and short bristles to a pure-breeding line that has brown eyes and long bristles.

Give the genotypes of the pure-breeding parental flies and the genotype(s) and phenotype(s) of the F₁ progeny they produce.

Accepted Answer

Hello, everyone and welcome to today's video. So we observed in the garden that green seeded over K GPS are dominant over yellow seeded which is lower case GP and purple flower, which is upper case PP are dominant over white flour, which is lower case P. Peace. If we cross dominant, true breeding, peace and recessive true breeding piece, what will be the genotype of the offspring in the F one progeny? So as answer choice A we have heterozygous for GNP as answer choice B we have homozygote dominant for GMP. As answer choice C, we have homozygosis for GMP. And as answer to is D we have heterozygote for G homozygote dominant for P. Well, in order to solve this problem, what we need to do first is determine the genotype of the parents. We're told that one of them is a dominant true breeding pie. Therefore, it is going to be fully dominant for both traits which are going to be GMP. Let's write that down. Then this is going to be crossed with A P that is going to be recessive through reading for both traits. So let's write that genotype down as well. Now we can make the cross. But instead of doing it as a di hybrid cross, we're going to be using one punt square for each of the traits here. So let's introduce into this problem. 22 by two punt squares that we can use to create this cross. Let's make the 1st 14 G here to the left. So on the top, we have the homo cycles dominant. On the side, we have the homozygosis. Once we make that cross, we can see that all of the offspring is going to be heterozygous. So that is the genotype that we're going to be having for the offspring in terms of the tray or the gene G. Now let's move on to the gene P. On the top, we have the homo cycles dominant on the side. We're going to have the homozygous recessive and we're going to see that once we perform this cross, we're going to have something similar occurring, all of our offspring are going to be heteros saga for peak. And therefore the offspring of these cross are going to be heterozygous for P. This is going to be their final genotype. Looking at our answer choices, this is going to be represented by answer choice. A heterozygous for G and heterozygous for P. I really hope this helped and I hope to see you on the next video

Key Concepts

Genetic Linkage

Genotype and Phenotype

Drosophila Genetics

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