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.