Many traits of economic or medical significance are determined by quantitative trait loci (QTLs) in which many genes, usually scattered throughout the genome, contribute to expression.

What general procedures are used to identify such loci?

Video transcript

Hi everybody. Let's take a look at this practice problem together. Which of the following are the chromosome specific DNA markers that can be used to find and map quantitative tree lo sai. Alright so let's review some terminology before we look at our options. So DNA markers, they are known chromosome locations for particular DNA sequences and they can be used to find and map Q. TLS. Now Q. TLS, what are they? It always trips me up because it's a pretty long term. But let's break it down. A quantitative trait is also known as a complex trait. Well what is a complex trait? It's a trait with variable phenotype IQ expression in a population and low side refers to location. And so this could essentially be complex trait location. So Q. Tl is the location of the genes that control phenotype. Pick expression of a trait. So what are the D. N. A markers that can be used to find and map those Q. TLS. Let's look at our options. We've got a micro satellites now recall that microsatellites are short repetitive DNA sequences that occur in a row with many locations all over the chromosomes. They are useful as genetic markers. So a is a correct answer. Then we have B restriction fragment length polymorphisms also known as R. F. L. P. S. Now R F. L. P. S. They are D. N. A sequence variations recognized by restriction enzymes. They produce different lengths of DNA sequences and they can also be used as genetic markers. Then we'll discuss C. Single nucleotide polymorphisms. Now they are the most common genetic variation in people and A. S. And P. Or pronounced snips is a difference in a single nucleotide base in the D. N. A sequence, and they are also useful as genetic markers. And so the last option D is all options are correct. So the correct answer is D microsatellites, RFLP, s and snips are all D. N. A markers with phenotype IQ variability that helps us compare genetic differences between individuals. Alright, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.