An association of racehorse owners is seeking a new genetic st...

Question

An association of racehorse owners is seeking a new genetic strategy to improve the running speed of their horses. Traditional breeding of fast male and female horses has proven expensive and time-consuming, and the breeders are interested in an approach using quantitative trait loci as a basis for selecting breeding pairs of horses. Write a brief synopsis (∼50 words) of QTL mapping to explain how genes influencing running speed might be identified in horses.

Accepted Answer

Hey, everyone. Let's take a look at this question together in Q T L mapping. How are the sources of DNA for genetic markers identified? And how are data for the quantitative trait of interest derived? Is it answer choice? A using DNA recommit in technology. Answer choice B examining the genome of an organism. Answer choice C using a database of genome sequence or answer choice D using the parents and progeny from controlled crosses. Let's work this problem out together to try to figure out which of the following answer choices is the correct answer. So we want to determine in Q T L mapping, how do we identify the sources of the DNA or those genetic markers as well as how is that data or the quantitative trait of interest derived? Well, first, we can cross off answer choice. A since answer choice A is incorrect because DNA recombinant technology is a method of combining different sources of DNA material and not a way to identify those sources. So it is incorrect. And we also know that a way to identify how the Q T L s influence a phenotype. The researchers can conduct a cross of two parental lines that differ in the specific phenotype. For example, if the researchers want to identify those Q T L s that influence large fruit size in tomatoes, they can conduct a cross between two parental lines of tomatoes that differ in fruit size, which the fruit size is that specific phenotype. And since those researchers are crossing two parental lines that differ in the specific phenotype, that means that the researchers are conducting a cross in which they know what the parental lines are, which describes a controlled cross, which means that in Q T L mapping, the way that the sources of DNA for genetic markers are identified and how the data for the quantitative trait of interest is derived is by using the parents and progeny from controlled crosses, which is answer choice d the correct answer. Since a controlled cross of parents with those known parental lines produce progeny, that can be used in a back cross to one of those parental lines allows us to identify the sources of the DNA for the genetic markers as well as determine how the data for the quantitative trait of interest is derived. I hope you found this video to be helpful. Thank you and goodbye.

Key Concepts

Quantitative Trait Loci (QTL)

Genetic Mapping

Marker-Assisted Selection

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