The mutations called bobbed in Drosophila result from variable reductions (deletions) in the number of amplified genes coding for rRNA. Researchers trying to maintain bobbed stocks have often documented their tendency to revert to wild type in successive generations. Propose a mechanism based on meiotic recombination which could account for this reversion phenomenon. Why would wild-type flies become more prevalent in Drosophila cultures?

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Accepted Answer

Hey, everyone. Let's take a look at this question together. Duchenne muscular dystrophy is an excellent disorder characterized by deletion or duplication in the dystrophin gene. Which of the following is true with regard to Duchenne muscular dystrophy. So let's recall what we've learned about what Duchenne muscular dystrophy is and take a look at the following statements to figure out which of the following are true. So we know that Duchenne muscular dystrophy is a genetic disorder that causes muscle degeneration and weakness because of alterations to a protein that is called dystrophin. And we know that these alterations are either a deletion or duplication. And so answer choice A says those deletions or those duplications that don't disrupt the reading of the dystrophin gene, but result in a non functional protein. We know that that statement is not true because those alterations to the gene will lead to an abnormal but still functional gene. And so answer choice A is not true. Answer choice B says frame shift mutations that include premature stop code ons of the dystrophin gene will not affect the protein structure of dystrophin. We know that that is also an incorrect statement because these frame shift mutations that include the premature stop code ons of the gene will lead to a completely dysfunctional protein or possibly no protein at all. So, answer choice B is not a true statement. Either answer choice C says females that carry the dystrophin mutation rarely express the disease. Well, since this genetic disorder is an excellent disorder, and we know that in female specifically, we experience that X inactivation to create that genetic balance. And so because of that X inactivation, we can actually see that the normal gene because it is X linked can B inactive. Since that X inactivation is random, the X chromosome that has the normal allele could become the one that is inactive, which means that the one with the disorder is the one that is not inactive. And so females that carry the mutation rarely expressed the disease. And that is a true statement. So answer choice C is the correct answer. And lastly answer choice D is incorrect because we know that A and B are not correct. So it cannot be all of the above and answer choice C is the only statement here. That is true with regard to Duchenne muscular dystrophy. I hope you found this video to be helpful. Thank you and goodbye.

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Key Concepts

Meiotic Recombination

Genetic Drift

Selection Pressure