Hi. It's Mr. Andersen and in
this podcast I'm going to talk about blood types. Blood typing wasn't that big of deal
back in the day because when we were cavemen it didn't really exist this whole idea of
transfusing blood from one person to another. But with modern medicine it's actually becoming
a really big deal. Now you should know this. In humans the ones I'll talk about in this
podcast are going to be the ABO blood typing. And another one I'll talk about is the Rh
factor. But know this, that there are about another 30 other families of blood types.
And what are we talking about when we're talking about blood types? Well basically we're talking
about proteins that are found on the surface of our blood cells. Or our erythrocytes. And
so basically if we're looking at the ABO system if you are type A blood, which I happen to
be type A blood. That means that you're going to have an A protein or a specific protein
on the surface of your blood. If you are type B blood then you're going to have a B protein
on the surface of your blood. And this is just a comic version. They're going to be
really, really tiny. You wouldn't be able to see them. They're just little proteins
on the surface. Or glycoproteins that are found on the surface of the blood. So if you
think about it what if you're type AB blood? Well basically that means that you have both
types of proteins. And if you're type O that means that you have none of these specific
proteins that are found on your blood. And so each of these have arisen through our evolutionary
history. But they actually are really important when we're trying to move blood from one person
to another. And that's because of our immune response. And so if you're type A blood, and
so let's remember that that's that purple kind of a protein, that pointy purple protein.
Well basically you're going to have that type of blood. But you're going to have antibodies
for the other type, the B antibody we call that. And the reason why is that you have
antibodies for every shape possible except the shape that you actually have. And so we're
not going to have purple antibodies. But we're going to have these B antibodies. And that's
just because we don't have the B protein around. Likewise if we look at type B blood. It's
going to have the B proteins but it would be silly for us to have those B antibodies
because it would just simply attack our own blood. But instead we're going to have the
type A antibodies. If we look at somebody who's type AB blood. Well, since they have
both of these antigens or both of these proteins on their surface, A and B, then we really
wouldn't want to have any other antibodies because again they would attack our blood.
And then finally if you're type O, basically if you're type O, since you don't have either
of the these proteins, then you're going to have antibodies that match up that specific
shape. And so again, the antibodies are there simply to protect our body against invasion
or against invaders. And so now let's look at type A. Let's say you're type A blood.
And so we said we got the purple pointy proteins. You're going to have the B antibodies. Let's
say that we give that person type O blood. Well what's going to happen? Well since there
are no proteins on its surface nothing will happen. So it's okay to transfer type O blood
to somebody who is type A. Nothing happens. But let's say we give them type B blood. Well
that type B blood is going to have the B proteins and so basically those B antibodies are going
to grab onto it. They're going to attack that. And we could die as a result of that. And
that's why it's important that when we're giving somebody blood transfusion we make
sure that we type their blood. Because otherwise their antibodies are going to attack it. Let's
say now we've got type B blood. Again, we've got the A antibodies, let's say we give that
person A blood. Well you can probably figure this out. Basically all of those antibodies
are going to glom on to that type A blood. And so we could die as a result of that. Now
let's look at somebody who has type AB blood. Well let's give them type A blood. Well since
they have no antibodies, at least for this protein, nothing would happen. Or if we give
them type B blood, nothing will happen. Or we give them type O blood. Nothing will happen.
And so we like to think of AB as the universal recipient. In other words, it can get blood
from any other type and it's going to be fine. But if we look at type O blood. Type O blood
since it has the other antibodies. If we throw anything with a protein, especially like AB
blood you can wee that all the antibodies are going to grab on to that. And so it's
really important when we're giving blood from one person to another that we match that blood.
Now if you're trying to solve genetics problems using blood, you simply have to memorize this.
Because it's really hard to just answer questions dealing with blood type unless you understand
the genetics behind it. And it's not simple Mendelian genetics. So basically there are
four different phenotypes. So you could be type A, B, AB or O. But there are six different
genotypes. And so if you're type A, like I am, you could be A because your have both
of these alleles for A or your homozygous. Or you could be heterozygous. You could have
one of the alleles for the A protein but the other one doesn't make a protein at all. That's
how you get the type O. If you have two alleles and neither of those express the protein.
If you're type B, again you could be homozygous for both of those or you could be heterozygous.
But if you're type AB blood then you're going to have to have one of each. And so we call
this expression, well multiple alleles because we have more than one allele, we have three
in this case. And also it's codominate. Because if you're type A and B, you don't have like
one being dominant. You're actually expressing both of those. And so if you're ever trying
to solve problems, they're never going to give you this genotype. So you really have
to memorize this. I or the AP folks are just going to simply ask you a question like this.
Is it conceivable that we could have a father who is type A and a mother who is type O.
And they could have offspring that are going to be type B, we'll say for an example. Well
to solve this let's look at a couple of punnett squares. If you're type A, we just write that
across the top. So you could be this. You could be homozygous for that A. We know that
the O is going to look like this. And so we could figure out that all of the offspring,
if the parent is homozygous is going to be type A. But if we kind of delete that a second.
Let's say that they are heterozygous for it. Let's say that person whose type A is going
to be like that. And then O looks like this. Well we could get this possibility. This person
would be type A blood. But we could also get this possibility. With this one being type
O blood. Or you could solve questions like this. Let's say that we have one parent who
is A and one parents who is B. What possibilities could we have for their offspring? Well, let's
look. If one is A and one is B, if they're both homozygous then we would have AB blood
for all of their offspring. But let's set it up another way. Let's set it up like this.
Let's say that one is heterozygous for it, like that. And then the other is heterozygous
for that trait. So let's say dad is B but he's heterozygous for that trait. Well, if
we look at this possibility in fertilization this person would be type AB blood. This person
right here is going to get the A from up here and the i from over here. So this would be
type A blood. This one right here would be B blood. And then this one right here, since
you're getting both of these little i's is going to be type O. So if you have an A and
a B you conceivably could get AB, B, A or O type blood coming from that. And so make
sure you understand the different genotypes that we have. Especially up here for those
who are type A and type B. Next thing I want to talk about is quickly the Rh factor. Rh
is simply another set of proteins. This is a little simpler to do genetics problems with
Rh factor, because you either have it or you don't. Either you're Rh positive, and you
have these Rh factors. Rh came from, they did some early studies on the rhesus monkey
to identify this protein. Rh negative you don't have it. And so what antibodies does
an Rh+ going to have? Well neither. It's going to have none of those antibodies. But if you're
Rh-, then you're going to have those Rh+ antibodies. And so the genetics are pretty simple. If
you're Rh+ you could be either homozygous or you could be heterozygous. If you're Rh-
then you're going to be homozygous negative. So which is dominant? Dominant is going to
be the Rh+. And so if we have a parent, two parents who are Rh+, is it conceivable that
they could have offspring who are Rh-? For sure. If they're both heterozygous we could
just go like this. These would be the offspring. This one would be Rh+, Rh+, Rh+ and this could
be a Rh-. And so the genetics are pretty simple but there's something you really want to be
aware of. Now, if we've got a mom right here. And let's say she's Rh-. And then we have
a dad who is Rh+, is it conceivable that they could have an offspring who ends up being
Rh+? Well for sure. And so basically what happens is during the first pregnancy, nothing
really happens. Because we're only sending antibodies in one direction. From mom to baby.
But during child birth, there's a lot of blood that gets mixed. And so basically what can
happen is during subsequent pregnancies, now mom is going to start building up a lot of
these Rh+ antibodies. And so during the second pregnancy she could actually be sending antibodies
that could damage that fetus. Now if we know this, which we do in developed countries,
then we can simply give her a chemical during I think the 28th week of gestation and then
we can suppress that immune response. But it's really important that we know that. And
so now we finally get to this last big chart. And it's got some really cool information
on it. If you look here it's got the donor and the type of blood they have. And then
the recipients and whether or not you could get it or you couldn't. And so if we look
at somebody right here, let's say we're giving O minus or O- blood, well we could give that
to all these people. From O all the way to AB. And so that's why we call that O- the
universal donor. And then if we look down here at AB +, well AB+ could get blood from
all of these different types. And so we call them like the universal recipient. And so
who would they love to see as far as donating blood? It's going to be somebody who's O-.
And what percent of the population is that? 6.6%. And so if we look at some of these percentages,
what's the most common? The most common is going to O+. Almost 38% of the population
is going to have that. Same with A+. And then we're going to have some more obscure blood
types like AB- where it's less than 1% of the population that has that. But there's
something unique. If you look at some native population, like native Australian Aborigines,
we find that B really didn't exist before Europeans showed up. And the same thing in
Native Americans. And so we can look at these proteins, that really don't have a function,
or maybe they have a function that's lost. And we can kind of trace human ancestry. So
that's blood typing. It's important when we switch blood or when we're trying to solve
some genetics problems. And so I hope that's helpful.
