By the way, welcome to video lecture, I guess, number 11. Number 10.5. Alright, video lecture 10 and a half. So it's kind of a sandwich in between video lectures 10 and 11. And this is a little different, so we're going to use the whiteboard to kind of talk it through.
than PowerPoint. And what we're going to be talking about is blood typing today. And we're going to use blood types as an example of some genetics that are based off of two things. One, more than two alleles, and two, about a pattern of an inheritance called co-dominance.
So normally we would do two alleles right like blue or brown eyes, black or white fur. We kind of just have like two alleles. In this situation blood types you guys probably know there are actually three possible alleles.
And so when we talk about blood types we have to keep that in mind. You've got your A, B and then O. You've probably heard of these as your blood types before right.
You could be A, B, B, B, B, O. What's your blood type, Mr. Jones? I'm O positive, which is the most common. Wow. I think like 35% of all people in the U.S. are O positive.
It's the most common. But as far as the genetics here, you're going to be filling out a table that looks like this. You can find it at the bottom of your skeleton notes as we go through the video lecture. So these are the first three.
Go ahead and fill in the other three based off the possible combinations that you can imagine. Because remember, each person needs... needs two alleles. And you can get two of any of these three depending on which ones you get from your parents. These are all the possible alleles combinations you can have and they are our genome types.
So these alleles represent different proteins that exist on your red blood cells. So your blood type is based off of the kinds of proteins that your red blood cells are making. So Mr. H will show us.
little bit about yeah and there is a room actually on your skeleton notes so what I'm about to draw I'd like for you to draw as well okay I'm gonna use red so whenever you see this RBC red blood cell so this is going to be our a alright this is gonna be our B, this is going to be our... A, B, and then this last one that I'm stretching for is going to be our O. So these are our four different phenotypes. So what I want you to know about is there's something called an antigen.
So an antigen would be like a protein that's basically kind of almost like a self-identifier. So it's sticking out of that red blood cell kind of being like, hey, this is what I am. I'm just making up these shapes.
We can say that one is an A antigen. So A blood type has A antigen. B blood type will have B antigen.
So what do you think AB has? Both. So we have an A, and then we have a B, and then here's kind of a tricky question.
What do you think O has? So, I don't know. Did we mention the relationship between these three alleles?
We might have forgot to mention that at the top. So we did forget to mention, so A and B, as we see here, are co-dominant because they both express the antigens. But we forgot to mention... O is actually recessive to both A and B.
So if O is recessive to A and B, it's not going to really show up the way you would expect it to show up. So it's a little bit of a trick question. But what would it look like?
So I remember too, adding to what Mr. Jones is saying, that when you have a situation where it's co-dominant, both of those are going to show. So the situation, as Mr. Jones mentioned, A and B are co-dominant to each other. So it's possible for both of them to actually show. show up but also as he mentioned O is going to be recessive to them so in a situation like this what's really interesting about O which is mr. Jones's blood type is that there's actually no antigen sticking out of that red blood cell so basically looks just like that there's nothing different about it So those are your four blood types and what they look like. So we can actually fill in some more of this chart now.
So let's quickly do that. So look down at your chart and we can actually fill out the next two rows here, the next two columns. So when we drew these, we kind of showed the different phenotypes.
So remember, if you have, if your genotype. There's two A's, then your blood type, your phenotype there is, you have blood type A. A, O, because O is recessive, blood type A.
If you have A and B, codominant, so your blood type is A, B, because they're codominant. They both show up in the phenotype. Right, so we can see here, AB codominant, we have two antigens. If you're BB, then you are phenotype B. If you're BO, you're also B, because it's recessive.
If you're OO, if you have two recessive alleles, your blood type is just O. And then you can fill out your antigen column as well based off of the drawings that you made. So any blood type that you see that's A, it has the A antigen. Blood type AB has both antigens.
Now I'm not going to write AB, I'm going to write A plus B. So A and B. For B, we know that's the B antigen and the B antigen.
If your blood type is O, you have no antigens. So we'll just write none. So that's the idea between the genotype, phenotype, and antigen.
So hopefully that makes some sense. You notice that there's one last column in our first table that we need to fill out about antibodies. Alright, so let's go back to... red blood cells so I'll use a different color for this one now so as Mr. Jones mentioned these antigens basically are going to tell you what the red blood cell is however there's something else is called antibodies you could separate your red blood cells from antibodies so keep that in mind as we go through examples in the future with blood typing so antibodies so should they be drawing these into their diagram yes please thank you for mentioning that so hopefully you had this you've drawn this already if not go ahead and pause real quick and draw that if you've already done it keep going so now let's talk about the antibodies so if you have blood type A you're going to sort of have them opposite of that which in this case is antibody B.
So what do antibodies do? Good question. So antibody B. This notice how I drew it the same shape sort of as antigen B. So if an antibody and an antigen kind of click on to each other it's not good news.
Basically if that happens you're getting clotting and in a worst-case situation your body goes into shock and you die. So these antibodies are part of our immune system, right? Yes. And so they, each antibody is very specifically shaped to match a certain antigen, right? So the idea is like, it's a good thing for our, to have antibodies to fight off foreign invaders like viruses or bacteria.
But obviously if we have red blood cells that have an antigen on them, we also don't want to be making the same antibodies because then we would be attacking ourselves. That's right. And so... So what anti... So we have to figure out what antibodies people make if they have certain blood types.
That's right. So for example, Mr. Jones mentioned that he's O positive. I am B positive. So once I teach you this, I want you to figure out, can I give blood to Mr. Jones or can Mr. Jones give blood to me?
Yep. All right. So our A anti... Or excuse me, our A blood cell has B antibody. Now B blood cell is going to have...
an A antibody. Notice how I drew it in a shape where this and that kind of click onto each other if they met. Okay? So the question is what do you think AB has? If it had an A antibody or a B antibody it wouldn't be good news, right?
You don't want to carry the antibody that's going to basically clot your own blood. So blood type AB actually does not have any antibodies. No antibodies. And hopefully that serves... as a hint for you to know what O has.
So O doesn't have any antigens. Which antibody or antibodies do you think it has? We got A, N, B. We got both. Cool? So let's fill in our table here so that we can keep moving on.
So if your blood type is A, you will have the B antibodies. If your blood type, so for both genotypes, our blood type is A, A antigen, B antibody. Notice that it's the opposite. If my blood type is AB, B, I have both antigens, so I cannot have any antibodies related to A and B. Now, I have other antibodies for all sorts of other things, but as far as blood type antibodies go, I don't have any for my blood type.
If I have blood type B, I'm going to have, like, A antibodies, just like we drew over here. And finally, if I'm O, I'm going to have A and B antibodies. So that's what your table should look like when you've completed it on the front page. All right. So you should be able to complete all of the front page of your skeleton notes at this point.
So if you flip it over to the back page, there's a little section there for number five where it talks about blood transfusions. So it's asking what kind of blood can each of these people receive. So kind of getting at the question that you were asking just a second ago. So I would like you to pause the video there and see if you can complete part five of your skeleton notes.
What can each of those... type of people receive. Remember, keep in mind that if I'm blood type O, I am producing and I'm making antibodies to fight off A and B blood, right? So if my, so I have these antibodies that are really good at attacking the A antigen and this is really good at attacking the B antigen. So that tells you something about what I can receive as far as blood because I have things that will attack.
certain blood types. So your job now is to sort of figure out that through number five. So it turns out that the positive and negative part of a blood type is related to something called an RH factor.
just another gene that has two alleles. It has the positive and it has the negative. So it's kind of like a regular genetics problem, it's a complete dominant situation.
It's not like the co-dominance of the A, B and the O. This is just regular dominance. So when we look at the table, I give you the middle aisle, or the middle row rather, where it says Rh plus Rh minus genotype.
That gives your blood type an Rh positive because it's positive is dominant over negative. By the way, the Rh comes from rhesus monkeys, and that's basically a research that was done to kind of figure out positive, negative, and because it was done on rhesus monkeys, they stuck with Rh or D. Yeah, so the Rh factor is this idea of positive and negative and the antigen that will show up is something called the D antigen. So do you want to draw that on our blood cells just to complete that diagram?
So you could flip it over probably back to your diagram to complete it. So let's say that this first one is A positive. By the way, please stay away from saying A plus or A minus because these aren't grades, they're blood types. So A positive is going to have... Draw that very well.
It's going to have a D antigen. Okay? Let's say this one is B negative. Is it going to have a D antigen? No, it is not.
However, it is going to have... D antibody. This next one let's just call it AB positive. What we'll see is it has a D antigen and it continues to not have any antibodies.
This is a very sort of unique kind of special case where you have all available antigens and no antibodies. And then here we can do Mr. Jones's O positive. So this one would finally have an antigen on it, but it wouldn't have that antibody. So if it has the antigen, it will not have the antibody. That's kind of a rule of thumb thing to remember.
You can't have both. So should this have the, so the only one that has the antibody is a negative blood type. Negative blood type. So let's just quickly fill out our table.
So we know that it's possible to be Rh plus, Rh minus. The other possibilities are... obviously plus plus which gives us a positive phenotype and the antigen there would still be the D antigen and then last possibility is to have two negatives which gives us a blood type that's negative.
Antigen, none. So it does not have the D antigen. Antibodies is going to be the opposite of the antigen. So if I have the D antigen, I cannot have the D antibody.
So both of these should be none. Here, I have the D antibody. So basically you've got two different situations.
You've got AB and O which is one sort of gene that codes for three possible alleles. And then you have the plus and minus which is another gene. Together gives you your full blood type.
That's right. So this is actually a good time for us to be able to figure out can we give each other blood? That's true. So let's do a quick little example.
So Mr. Jones, you said you are... I'm O positive. O positive.
So the question is, can you give me blood? So the way that I do this is actually draw out the whole thing because I don't want to make mistakes. So here's my O. Positive. Notice how I only drew the D antigen.
It doesn't have the A and the B. It's just O. So what antibodies will I have?
In this situation, it doesn't matter. Because when someone's giving blood, you can actually separate the antibodies. from the actual red blood cell.
So it's only, so the antibodies are only important in the receiver, the recipient. So it doesn't, so when I give my blood to you, I'm not giving you my antibodies, I'm just giving you my blood. cells. Exactly. So if Mr. Jones had antibodies here, and you can determine whether he does or not, I wouldn't be getting those anyway.
Alright? So, my blood, so I'm going to be B positive, so I'm going to have B, and I'm going to have a D. Do I have any antibodies? I have an A antibody.
So the question is when this blood comes into contact with my antibodies do I have an antibody that's a perfect match for one of those antigens? It looks like I don't. So this is actually doable. I can give you my blood.
Can I give you blood though? That's the question. So if we want to go the other way, we have to know what antigens I have.
So what do I have for antigens? Or sorry, what antibodies do I have? Antibodies.
So you are going to have A. Yup. And you are going to have... B. I have A and B antibodies.
Alright, so if I'm giving you blood now, so our arrow is going the other way. Switch it up. Yup.
And now remember, my antibodies don't matter anymore. Right, so you're just giving me your blood cells. Yup.
So do you have an antibody that's going to attach to one of my antigens and cause clotting? Oh yeah. Yup.
It's B. You got B. Mr. Jones, I am sorry but I cannot give you blood. This is, this reminds me of our friendship in a way.
It kind of is. I'm sorry. I'm sorry.
I can give to you, but you cannot give to me. That's correct. It's just a lifestyle thing. That's actually not very true.
I think we have a mutualistic relationship. We do, yeah. This is definitely just a blood thing.
Alright? Alright. And then the last thing I just wanted to go over real quick. I just wanted to teach you how to do a Punnett Square when it comes to...
blood. So for example, you know, we talked about the genotype AA. The way you write it for Punnett squares, this AA, the proper way of writing it is actually like this, IAIA. So what does the I stand for?
I don't actually know to be honest with you. Okay, but that's just the way we write it. So the I, so that means I have one A allele on my ompf as one copy and my other copy is another A allele?
That's right. So if someone's like AB, right? It's gonna be IA. I be. Okay.
Right? So we'll stay away from the sort of positive negative right now. We'll just, let's say someone who is blood type, let's say. Let's say you and I have tried to have a child. Okay, I like that, I like that.
Alright, so you are what, O positive? I'm O positive, but we're going to ignore the O's, okay. Exactly.
We're going to ignore the positives and negatives. So if that's your phenotype, what would your genotype be? Would I write I-O-I-O? Good question, you would actually not write the O's. I would not write the I's?
Yeah, you would just write the I's. You just have two I's. Okay, so I am going to be B, because remember we're keeping away the positives and the negatives right now.
I'm B, what am I? B. IB, how do I know? Exactly. Are you IBI or IBID? The only way to know is by knowing what my parents had, right?
So I don't technically know which one I am, so we can just kind of choose one. Okay. But let's go over both options. So I could be IBIB. This would make me homozygous.
Or I could be IBI, which is basically like saying BO. Right. Okay. It's kind of weird.
All right. So I could be IBI Let's just say that I'm heterozygous. Let's go ahead and do this Punnett Square. Okay. Alright.
Do a little cross action. Do a little cross action. Alright. So let's say Mr. Jones goes here, so these are all the possibilities, I-I, and we'll go with I-V-I for me, so this is the heterozygous one, so I'll go I-V-I, and then let's bring them together.
We go I-V-I in this box, notice I brought those together, then we go I-I there, I-V-I here, and I-I there. Okay, so... Well, you have one thing that doesn't look quite right to me. What do I do?
What do I do? Did I make a mistake? This box.
That box. What's wrong with it, Mr. Jones? I think it should be I-I.
Right. Anybody catch that? I'm gonna keep you on your toes. Keep you on your toes. Alright.
Mistakes anywhere else? Yes. Where else?
Right here. What's the problem? You forgot the B. You're right. IBI.
So, what do these give me? What phenotype do these give me? Right? Because that's my genotype.
Yeah, so your phenotype would be B. Mr. Jones, how come it can't be B-O? Because that's a genotype.
That's a genotype. So really, the phenotype here would be... What about these?
Give you O. Why can't it be O? It's a genotype.
So if we had kids, there'd be a 50% chance that our kids would have phenotype B or phenotype O. Alright, cool. I think that's it. I think that's it.
Thanks for watching. If you have any questions, let us know. Alright, bye guys. The unit type is here, basically O.
The unit type here is going to be O. The unit type here is going to be B. The unit type here is going to be B. Good idea!
Let's do that part again. You did it. You did that move there.