Describe how having the Cas9 gene at a genomic locus unlinked to ...

Question

Describe how having the Cas9 gene at a genomic locus unlinked to the guide RNA and target site locus in an engineered gene drive system (see Figure 15.23) could slow the propagation of the gene drive allele in a population into which a small number of individuals carrying both the gene drive allele and the Cas9 locus are released.

Accepted Answer

Welcome back, everybody. Let's look at our next question. Which of the following statements about gene drive alleys is true choice. A 50% of the offspring inherits each of its two alleys. Choice B, they follow the Mendelian segregation pattern. C, they maintain the Allal frequencies or D they induce a biased inheritance pattern. Well, let's recall what gene drive alleys are and these are essentially what you might call. And I'll put in quotation mark selfish genetic elements and they actually influence the processes of gametogenesis or reproduction to increase their rate of transmission. So we know that in normal reproduction passing on of genes, um the offering inherit one gene from either parent, they have a 50% chance of inheriting a particular alley. When you have a gene drive all, you have a greater than 50% chance of inheriting that all. And this can happen because these alls have actually evolved molecular mechanisms that make them more likely to be passed on. And these can either happen by converting the wild type allele to the gene drive allele or by reducing the fitness of the wild type all. And all this sounds a bit wacky um One of these mechanisms where this might happen is if the gene drive allele involves, has an endo a that causes the chromosome to be cut in the region where this allele is. And it essentially cuts out the wild type ally, forcing a repair process that repairs that region with the gene drive allele instead, essentially converting the wild type ally to a gene drive allele. And these mechanisms can occur in nature when they evolve, evolve, excuse me, or they can be synthetic. And you might be thinking when you heard me describing the mechanism for cutting out the wild type. All that sounds awfully similar to that CRISPR cows process used in gene therapy. And that is true. So important to remember that these can be synthetic, used to direct um inheritance of something. Sometimes it's used uh for vector control, for instance of insects, but it can also occur in nature. So let's look through our answer choices to see which one is the true statement about these gene drive alls. So should I say 50% of the offspring? And here it's each of its two alleys is not correct because of course, the dream drive alley is results in greater than 50% of the offspring inherits the gene drive value. Choice B, they follow the Mendelian segregation pattern also not true because this throws off Mendelian inheritance by influencing inheritance in the direction of the gene drive value. So I see they maintain the Allal frequencies again, not correct. Since that they're tipping the balance in favor of the gene drive all. And finally, choice D they induce a biased inheritance pattern. This is correct because they biased the inheritance towards the gene drive alley. So choice D the biased inheritance pattern is our answer here. See you in the next video.

Key Concepts

Gene Drive Systems

Cas9 and Guide RNA

Genomic Locus and Allele Propagation

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