For this question. We're trying to understand how C T cells were to present antigen from different strains of, say, a flu virus. So in this experiment, they're using two different flu virus strains. They have a 1968 flu virus and a 1934 flu virus. And what they are doing is they are making proteins from the genetic sequences of each of these, and they're finding out that the 1968 gives a response by the T cells, whereas the 1934 strain has no T cell response or very little. And this is measured by the number of cells that are being Liszt when they contain the proteins from each of these flu strains, so they give us a graph. To represent this, they have the number of cells, or the percent of cells, life on the Y axis. And they're presenting us with multiple bars measuring the number of cells being laced so they have a bar for the 1968 virus, a bar for the 1934 virus, and you can see there's a significant difference between the number of cells BIST for each of these strains from there they are measuring the number of cells that lies when they contain a certain amino acid sequence. So the first section is for cells containing amino acids from the 1968 stream. But as the second sequence of bars are amino acid sequences from the 1934 strain. So as you can see in the 1934 strain, you have two different sequences. You have a 3 65 to 3 80 and you, of course, have a 3 69 to 3 82. And both of these have very little cell isis among all the cells, whereas in the 1968 we have three different bars, the most significant ones being the one showing many cells being Liszt, which is the 3 65 23 80 and the amino acid numbering sequence. And you also have 3 69 23 82. So between these two amino acid sequences, the difference between each of these is causing this significant change in the number of cells being recognized by your T cells and being Liszt. So the main difference in amino acid sequence between these two it's going to be those first few starting amino acids. So here, for the first part of question a the amino acid sequence responsible for this T cell recognition are going to be the amino acids 365 to 369. We know that 369 to 380 is not causing this response. Or else we would see the bar in this second part for the 1968. Also induce that large number of style license. So here for part two, a question A. We're also being asked why these other viral proteins do not cause this significant sell like Isis. That's because of the recognition of the anti Jinbei your T cells. T cells are not all powerful, and they're not going to recognize and induce apoptosis in all kinds of cells with viral antigens. It just so happens that they can recognize some sequences, and by chance, they happen to recognize the 365 2, 369 amino acid sequence. If they recognized all amino acid sequences, they risk the chance of endangering our own cells, which, of course, have sequences of amino acids. And this limited recognition kind of helps that specific response of T cells and prevent them from overreacting. But I say we have part B. It's asking us about how the MHC type one molecule works and how it's applied to this experiment. So if you remember how MHC molecule works specifically MHC one, this occurs in all living cells. And when they have, say, a viral strand inside their genomic structure, they're going to create viral proteins to have these be viral proteins. The cell is going to recognize that these viral proteins are not their own. They're going to connect them to an MHC molecule. And when it's complex with the viral protein, it's going to move it to the surface of the cell, where it can present this auntie gin to your professional antigen, presenting cells such as your B cells or macrophages, and that will allow for your cell mediated response and the like isis of the cells. So, in order for this to work for this experiment, they're measuring the number and percent of cells being laced. So the best way to go about this is there going to use a 96 well plate, which is basically just 96 specimen holders where they're going to have the infected cell on the inside containing these viral proteins. They're going to line these 96 well plates with the cells they're infecting, and they're going to infect them with different amino acid sequences. So this would be like an amino acid strands of 3 65 23 80. Or they might do the 3 69 to 3 82. And they're going to do this for each the 1968 strain as well as the 1934. And to make sure they can measure the number of cells Liszt. They're going to need a probe or some sort of marker that they can check inside of the well. So what they're going to do is to each of these amino acids, the viral protein or the viral genetic sequence they're going to infect each of these cells with is going to include what we call a probe or some sort of marker. So this could be a marker that has some sort of fluorescence. It could be some sort of radioactive marker, something they can use to detect and measure the amount in the super needn't or the remaining fluid in the 96 well plate. Basically, it's going to be included inside the cell, and if the cell lice is, it's going to be released into the fluid of the 96 well, plate, whereas if it does not light, it will still remain inside the cell, where it won't be measured in the fluid. So what they're going to do is there going to centrifuge each other? 96 well, plates, and they will get a button of live cells on the bottom, and they will get a number of the probe for the marker for the concentration inside of the fluid or the super name. So they're they're able to compare the number of cells they initially put in and compare that two. The amount of probe in the Super Natan, where this would be the inverse of it, will be the probe divided by the cells, and that would give them the percentage of cells that were laced. So here, for part B, they're going to introduce the virus and some sort of probe into the cells, and from there they're going to compare the amount of probe and the Super Matan to the number of cells they started with, and that's going to give them the percentage of cells that were Liszt in the solution. This way, they'll be able to reliably compare the number of live cells and not include that in the number of life cells they originally started out with.