Two theoretical genetic strains of a virus (a⁻b⁻c⁻ and a⁺b⁺c⁺) were used to simultaneously infect a culture of host bacteria. Of 10,000 plaques scored, the following genotypes were observed. Determine the genetic map of these three genes on the viral chromosome. Decide whether interference was positive or negative. a⁺ b⁺ c⁺ 4100 a⁻ b⁺ c⁻ 160 a⁻ b⁻ c⁻ 3990 a⁺ b⁻ c⁺ 140 a⁺ b⁻ c⁻ 740 a⁻ b⁻ c⁺ 90 a⁻ b⁺ c⁺ 670 a⁺ b⁺ c⁻ 110

Video transcript

Hey everyone. Let's take a look at this question together, bacterial culture was infected with two strains of a virus. One strain was minute turbid and acro flavin resistant. While the other one was wild type for all three genes, the resulting 10,000 plaques were distributed among the genotype listed below identified the order of genes. So let's first start off by figuring out the distance between um And T. You. And to do that. We're going to focus on the ones right here. So what we do is we add these up and we get 1920. Which we're then going to take that 1920 and divide it by the 10,000 plaques that were distributed because the total is 10, and multiply that by 100 Map units. And we end up with 19.2 as the map distance between M. And T. U. Next we're going to calculate the distance between T. U. And a. Which we focus on the ones listed here. And so the total of all of those when we add them up is 580. Which we then divide by that 10,000 again and multiply it by the 100 map units. And we end up With 5. map unit as the distance between T. U. And A. And lastly we want to calculate the distance between um And a. Which we focus on this one this one this one and this one. And so we add those up we get 1700 which we then divide by the 10,000 once again and multiply it by 100 map units. And we're left with 17 map units as the distance between M. And A. And so looking at the numbers that we have calculated here here and here, we can see that the distance between M. And T. U. Has the greatest map distance. So that means that the order of the genes is M. Followed by a followed by T. U. Which would make answer choice D. The correct answer. Because when we calculate the distance between the different genes were able to identify the correct order of genes which is M. Followed by a followed by T. U. So that would be answer choice D. The correct answer. I hope you found this video to be helpful. Thank you and goodbye.