in this video, we're going to begin our discussion on antibodies now. Antibodies play a big role in immunity, and for that reason, before we actually talk directly about antibodies were first going to do a summary on immunity to give you guys a little bit of context. Now it's important to know that organisms are continually subject to attack by pathogens that cause disease. And for that reason, it's important that organisms have a complex immune system to help defend against these pathogens that air constantly attacking. And so there are two general types of immunity. Innate immunity, which acts as the first line of defense, and adaptive immunity, which acts as the second line of defense now innate immunity because it acts as the first line of defense. It's a more generalized, non specific immunity that's used against all pathogens, and this includes the skin and mucous. Whereas adaptive immunity, on the other hand, is a much more specific type of immunity with both an adaptive and a memory component, and this includes both T cells and B cells. Now this adaptive immunity can actually be further split into two types. The first is cellular immunity and the second is Hugh moral immunity. Now cellular immunity is primarily going to target intracellular pathogens that make their way inside of cells using T cells. And Hugh Moral Immunity, on the other hand, is primarily going to target extra cellular pathogens on the outside of cells using antibodies and B cells. And so, really, this is the first point here where we're introducing antibodies into our lesson and so notice down below. In our example, we're showing you aim or visual display of the immune system summary that we described up above, and so you can see that the immune system can be split into two groups in eight non specific immunity, which acts as the first line of defense and includes defense against all pathogens on includes the skin, mucous and stomach acid. And then the second type of immunity is adaptive or specific immunity, which has at activity and memory and acts as the second line of defense. Now this adaptive specific immunity can be further split up into cellular immunity and Hugh moral immunity. Now, cellular immunity is going to defend inside of the cell using T cells, whereas Hugh Moral Immunity is going to defend outside of the cells using B cells and antibodies and so up above noticed that we're showing you over here on the left, a T cell that is going to attack intra cellular pathogens. And then on the right, we're showing you a B cell that is going to attack extra cellular pathogens outside of the cells. And so you can see right here is actually the structure of an antibody. And we'll be able to talk more about antibodies in our next video. So now that we've concluded our summary of immunity, I'll see you guys in our next video.

all right, So now that we've briefly summarized immunity in this video, we're going to talk about antibodies now. Antibodies are also commonly referred to as just immuno globulin is and abbreviated as I G for short and so antibodies or immuno globulin are just why shaped proteins that can recognize and bind to an antigens episode. But what in the world is an antigens episode? Well, an Auntie Jen is really just any substance or compound that can provoke an immune response, whereas an EP itto, on the other hand, is going to be a very specific and exact binding site on the anti gen that an antibody binds to. And so notice down below. We're showing you a bacterial antigens right here, which would just be the entire bacteria. But again, an antigen is any compound, so it could be a bacterial antigens. Or it could be a viral antigen or some other compound as well. And so notice that these specific shapes that are on the perimeter of the bacteria are representing Epitaph oats. And so what you'll notice is that the antibody over here, this y shaped protein is binding specifically to this orange capito Pope which is again the exact binding site on an anti gin than antibody binds to. Now. Antibodies have a very, very strong affinity to their episode, meaning that they have quite a low K d. And so they also will bind to the episode via and induced fit model. Now, as we mentioned in our previous listen, videos, anybody's are produced by B cells, and they're part of hue moral immunity for that reason, and so what you'll notice is down below. We're showing you this B cell here in blue and notice that the B cells can be physically attached to the B cells. Perimeter here, embedded in the membrane of the B cell. And the antibodies can still attach and bind to their episodes in this way. Or it's also possible that the antibodies can be secreted by the B cell, uh, into the environment, so that they are free and dissociated from the actual B cell, and so moving forward will be able to talk about these secreted anybody's further. Now it's important to note that anybody's are not only important for immunity purposes, but they can also be isolated for biochemical techniques such as Eliza's, which will talk more about later in our course. But for now, this is a brief introduction to antibodies. And in our next video, we'll talk Maura about the structure of an antibody, so I'll see you guys there.

So from our last lesson video, we already know that antibodies are why shaped proteins. But in this video, we're going to talk more details about antibody structure. And so anybody's actually consists of four poly peptide chains, two of which are identical light chains or L chains for short. And the other two are identical heavy chains or H chains. For short. Now, the light chains are actually much lighter than the heavy chains, which are much, much heavier and larger. Now these four chains are covertly linked together via di sulfide bonds. And so if we take a look down below at our image notice we have our Y shaped antibody right here and notice that are y shaped. Anybody has four poly peptide chains, It has this light chain that is identical toe this light chain over here, and then it has this heavy chain right here that is identical to this heavy chain right here. And so you can see that the heavier chains highlighted in green are much larger and therefore much heavier than the lighter chains which are much smaller and much lighter and mass, and also noticed that these four chains are covertly linked together via these die sulfide bonds that exists between the are groups of Sistine Residues. Now what's also important to note is that each of these light and heavy chains has a variable region also known as a V domain, as well as a constant region also known as a C domain. Now, the variable region or the V domain, is going to be located at the tip of each of the prongs of the why, and it contains the n terminal end of each of the poly peptide chains. So if we take a look down below at our image, notice that the V or variable domain is highlighted with the green background right here at the tips of the prongs of the why and notice that it also contains the end terminal end or the free amino groups of each of the four Poly peptide chains. Just like what we said up above now, what's also important to note is that the V Domain contains the anti gen binding site. So this is where the antibody is going to bind to the antigens at thes two potential positions indicated by the arrows. And so the reason it's called the V or variable domain, is because this region right here will actually vary between different antibodies. Now the sea domain. On the other hand, because it's the constant domain, it's not actually going to vary. It's going to remain constant, even between different antibodies. Now the sea domain is, of course, going to be the rest of the antibody. So it's gonna be located at the hinge and the stem of the Y. So if we take a look down below, of course, the sea domain eyes going to be the rest of the antibody here. And the C domain is important because it's actually recognized by immune system cells. And so, essentially, what happens is the V domain will bind to the antigens at these positions, and then an immune system cell combined to the sea domain. And so the antibody can act as an intermediate between the immune system cells and the antigens. Now, what you'll notice is in our image. Here we have. We have the V domain here with the V s on them, and then whether or not they're light or heavy chains is indicated by the L and the H, and so you can see that both the, uh, heavy chain here and the light chain has a a variable domain as well as a constant domain. And so what's important to note is that we can further break up the structure of this antibody if we imagine breaking the antibody at the hinge of the why. And so here, in a dotted red line, what we have is an imaginary line. If we were to break our anybody right at the hinge and what that would do is it would leave us with the top portion here, which we would refer to as the F A B region. And this is because this, uh, has the fragment that has the antigen binding site. So you can see we have the antigen binding site in this region. And then we're also left with the bottom half of the anybody down below, uh, which would be the F C region or the fragment that contains the constant region. So this would be the F C region, this bracket right here and so really, this is the structure of a typical antibody and we'll be able to get some practice applying the concepts that we've learned as we move forward in our core. So I'll see you guys in our next video

in this video, we're going to talk about some antibody functions now. Antibodies have many, many different types of functions, so we're not gonna be able to get into all the details of all of the different types of functions. However, some of the more common functions that your professors might expect you to know include neutralizing toxins and tagging invading pathogens for destruction by our immune cells. Now, fa go sites are specific immune cells that will engulf and neutralize pathogens that air tagged by our antibodies. And so notice down below, over here on the left hand side of our image, these little red balls that we see here represent viral antigens. And so these are indeed viruses that can cause disease. Now, these little y shaped structures that we see here in black are, of course, our antibodies. And so the antibodies will bind to the viral antigen and help make it Ah, lot easier for this fag. Oh, site here to ingest the viral antigens and neutralizing. Now notice that these little gray balls that we see here around the faggot site represent antibody receptors more specifically FC receptors and recall from our last lesson video that the FC region is just the region of the antibody that contains the constant region. So it's essentially the stem of the Y of the antibody. And so you can see over here that these little receptors are binding to the FC region of the antibody and helping to make it a lot easier for this faggot site to engulf the viral Auntie Jen. And then once the viral antigen has been engulfed, it can be destroyed and neutralized. Now, over here on the right hand side, what we have are additional, um, mechanisms of antigen and activation by antibody binding so additional functions of antibodies. And so, of course, anybody's can be used for neutralizing toxins and other, uh, antigens as well. So you can see here in yellow, we have a viral antigens and and read. Here we have this bacterial antigens and notice that our antibodies here are these y shaped structures that can bind to the antigens and essentially neutralize them, meaning it will make the harmful portions of these antigens ineffective and inactivate them. Now, a gluten nation we know from our previous lesson videos is just a fancy word. That means clumping and so you can see down below. Because there are two antigen binding sites on each of these antibodies, they can actually bind to two separate, uh, antigens. So here we have the bacterial antigens and you can see that the antibody combined to two separate bacterial antigens and help clump them together and that basically localizes these harmful bacterial antigens in tow one area again making it easier for our immune system to, um, essentially target thes antigens for destruction. And then, of course, uh, antibodies can also be used for many different types of biochemical techniques, including antigen precipitation. And so, if we had a specific antigen of interest in a solution such as this yellow ball here and we wanted to isolate this specific antigen from the solution, we can use antibodies, and the antibodies will bind to the specific antigen of interest and create a precipitate. And so this precipitate can be fairly easily isolated and purified, using ah, lot of the purification techniques that we talked about in our previous lesson videos. However, what you can see here, the main take away is that anybody's have lots and lots of different functions, but they're mainly used for immune system, um, destroying pathogens and then also for biochemical techniques such as antigen precipitation, as well as a technique that we'll talk more about later in our course called Eliza. So we'll be able to talk more about the different classes of antibodies in our next video, so I'll see you guys there.

in this video, we're going to talk about the different antibody classes. And so it turns out that there's actually five different classes of antibodies or, in other words, five different classes of immuno globulin. It's and so these five classes are based on differences in their heavy chains as well See down below in our table. And so the five classes of antibodies R i G I g A I g m i g e n I g d. And if you look at these red letters here, notice that it spells gamed. And so notice down below. Right here we have this anybody stick figure playing some video games and based on his facial expression, I'd say he's pretty gamed out from playing video games for 72 hours straight. And so hopefully this antibody stick figure, along with gamed will help you guys remember the five different classes of antibodies. And so, looking at this table right here, what I want you guys to notice is that the light chain for all five classes of antibodies is exactly the same. So the light chain, why, there'd be the one that's represented by the Greek Letter Kappa or the light chain represented by the Greek letter Lambda. And so the light chain is not going to distinguish one antibody class from another. However, looking at the heavy chain notice that each class of antibody has a unique heavy chain. And so it's the heavy chain that's going to distinguish one antibody from one antibody class from another. And so this first row of antibody, this first class of antibody is I G. And this is really the one that we've been talking about all along and so you can see the Y shaped structure here that we talked about. Now, notice that I G e n I G have very similar type of structures. Toe i G. However, I G a forms a dime er of these two y shaped structures, and I g m tends to form a Penta mur uh, containing five different y shaped structures here. Now, over here in this column, what we have is the primary feature of each of these antibodies. Now I G is actually the most prevalent and the most abundant antibody in our blood. So this is going to be one that's involved on protecting pretty much against all types of infections, including bacterial and viral infections. Now I g. A is actually going to be highly concentrated in mucus membranes, and it's going to be one that is typically secreted by ourselves, and it's also prevalent in our saliva. Now I GM, interestingly enough, is usually going to be the first antibody that's going to be produced upon infection. So I GM, is going to be the one that's going to initiate the primary immune response. So the very first immune response and then the common second immune response would be I G. Since it's so prevalent in our Bloods now, I g. E, on the other hand here, is going to be one that's going to defend against allergies or allergies. And so you can see here we have a guy who's saying I'm allergic to this kitty cat right here, and that's unfortunate because this is a cute little kitty cat, but again is gonna help defend against these allergens. Now I G. D. Is one where its function is not really very well characterized. However, there are some text books and studies that say they're involved with activating B cells and allowing B cells. Thio participate in immune responses. Now, over here on the far right, what we have is the distribution of these antibodies, uh, classes throughout our bodies. And so notice that pretty much all of the antibodies they're gonna be found in our bloodstreams. Except for I G, which again is going to be highly concentrated in our mucous membrane. So it's gonna be lining our digestive systems a lot. And so this here concludes our introduction to the antibody classes, and we'll be able to talk more about antibodies as we move along in our core. So I'll see you guys in our next video.

in this video, we're going to talk about antibody diversity. And so it turns out that our immune systems have the potential to produce an enormous amount of different antibodies, perhaps greater than 10 to the 18th or one quintillion, different antibodies. That's more antibodies than the estimated amount of individual grains of sand on our entire planet. That's a lot of antibodies that are immune system has the potential to produce. In fact, there's so many potential possibilities for antibodies that they all cannot be produced in one single lifetime. So here we have a question, and it's asking, how in the world is it possible that anybody diversity can be so large if humans on Lee have 25, genes, which is a much smaller number than one quintillion? And so the answer to this question is actually right here. And so anybody diversity actually results from significant amount of gene rearrangements, splicing and mutations. And so notice down below, over here on the left hand side, we what we have is DNA being shown, and this DNA is coding for an antibody, and so you can see that the different regions of the DNA are color coded to show you what part of the antibody that they express. And so notice that the original DNA appear has many different combinations for these different, uh, regions of the antibody. However, through splicing and rearrangements, we could get different smaller combinations, combining different features and even mutations in the DNA can create lots and lots of diversity. And so, through transcription of the DNA into RNA, you can see that even the mutation will carry over here and then through translation. What we get is the antibody being produced. And even a single slight mutation like this one right here can result in a different antibody being produced. And so we get a diverse antibody just through all of these gene rearrangements, splicing and mutations. And so this concludes our introduction to, uh, antibody diversity and in our next video will be able to talk about monoclonal and Polly clonal antibody. So I'll see you guys there

in this video, we're going to talk about monoclonal and Polly clonal antibodies. And so we already know from our previous lesson videos that antibodies are important for immunity. However, also recall the antibodies are valuable re agents for biochemical assays. But in order to use antibodies in biochemical assays, we must first prepare and collect the antibodies. And so really, there are two main types of anybody. Preparations that air used. The first are monoclonal. Anybody preparations and the second are Polly clonal antibody preparations. And so these monoclonal antibodies are going to be identical antibodies. And so mono is a prefix that means one or singular. And so these are identical antibodies. And because they are identical antibodies, they're going to be specific to the same exact EP itto on the same exact antigens and monoclonal antibodies air going to be made by B cell clones. And these be so clones can be grown and cell culture in a lab. Now, Polly clonal antibodies, on the other hand, are going to be a mixture of antibodies. And so Polly is a prefix that means many, and so this is many different types of antibodies, a mixture of antibodies and because these air different antibodies, they're gonna be specific to different episodes, but on the same exact antigens. And so, Polly clonal antibody, is there gonna be made by different B cells Now, an example of a poly clonal antibody preparation would be injecting just one single Auntie Jen into an entire animal. Well, that animal is going to have a B cell population with different B cells. And those different B cells are going to produce different antibodies that are specific to different epitope on the same single antigen that we injected. And so let's take a look down below. It are example to clear some of this up and notice on the left hand side. Over here we have monoclonal antibodies and on the right, what we have our Polly clonal antibodies. And so notice that these yellow structures here represent the antigen and the antigen as these different episodes that air present on them. And so when it comes to monoclonal antibodies, these are going to be identical to each other, and they're therefore going to be made by the same exact B cells. And so you can see here we have these anybody's that are identical to each other. And so these are monoclonal antibodies. Now, Polly clonal antibody is, on the other hand, are going to be different. And because they are different, uh, they're gonna be made by different B cells. And so you can see that we have some pink antibodies different to the triangular epitope on these same Auntie Jen. We've got these green antibodies that are specific to these grayish, uh, and episodes on the same Auntie Jen. And then, of course, we've got the blue ones as well. And so because we have a mixture of all of these different antibodies made by different B cells that are binding two different episodes on the same antigens, this would be a, uh, example of Polly clonal antibodies. And so that concludes our introduction to monoclonal and Polly clonal antibodies. And we'll be able to get some practice utilizing these concepts as we move forward in our course. So I'll see you guys in our next video