Blood TypingBlood TypingAgenda: Hand in the 3 incomplete dominance questionsSpotlightMultiple AllelesHow is blood type determined?Blood TransfusionsSolving basic blood typing questions.

Review of Last ClassReview of Last ClassWhat is the difference between

incomplete and co-dominance? In co-dominance both alleles are

expressed fully. Both parental phenotypes can be distinguished in the offspring

In incomplete dominance, both alleles are expressed to an extent, producing an intermediate phenotype.

What if a woman who was heterozygous for sickle cell anemia decided to have a baby with a man, who was homozygous for sickle cell anemia?

HbSHbN x HbSHbS

What would the F1 generation be? What are the chances their child

will have sickle cell anemia?

Multiple AllelesMultiple AllelesThe traits we have been studying

so far, have all been controlled for by one gene with two alleles (eg. eye colour or flower colour. )

Multiple AllelesMultiple AllelesMany traits in humans and other

species are the result of the interaction of more than two alleles for one gene.

These multiple forms of genes are referred to as multiple alleles

An individual can only ever have two alleles for each gene.

But in the population many different alleles can exist.

Blood TypeBlood TypeAn example of a trait controlled

for by multiple alleles on one gene, is blood type.

What are the possible blood types?

Do you know what blood type you are?

How do you know this?

What Does Blood Type Refer What Does Blood Type Refer To?To?In humans, a single gene

determines a person’s ABO blood type.

This gene and its alleles, determine what type of antigen molecule, if any, is attached to the cell membrane of red blood cells.

It is the presence of these antigens, which determine your blood type.

Type A blood contains A antigenType B blood contains B antigen

Type AB blood contains both A and B antigens

Type O blood contains neither antigen

There are three alleles coding for antigens on the red blood cell membrane.

The alleles can be represented by IA, IB and Ii

Recall from last class, the big letter represents the gene coding for the trait

While the superscript letters represent the alleles.

What can you conclude about the A, B and i alleles?What can you conclude about the A, B and i alleles?Which ones are recessive, dominant and co-Which ones are recessive, dominant and co-dominant to each other?dominant to each other?

Type A blood has these genotypes: IAIA, IAIi

Type B blood has these genotypes: IBIB, IBIi

Type AB blood has this genotypes: IAIB

Type O blood has this genotype: IiIi

IA and IB alleles are dominant over Ii allele.

IA and IB alleles are co-dominant because both alleles are expressed simultaneously.

Practice ProblemPractice ProblemImagine a mom, who is

heterozygous for blood type A had a child with her husband, who is homozygous for blood type B.

What would the probability of having a child with blood type A?

With blood type AB?With blood type B?

What is an antigen?What is an antigen?An antigen is a substance or

molecule that when introduced into the body triggers the production of an antibody by the immune system.

An antigen acts a marker for cells.The antibody, will then kill or

neutralize the antigen that is recognized as a foreign and potentially harmful invader.

AntibodiesAntibodiesTake the next minute to read the

chart and fill in the blanks

What Do Antibodies Do?What Do Antibodies Do?

What would you do?What would you do?Imagine you are on a hiking trip and

you cut yourself very badly. You are losing a large amount blood very quickly. Your friend suggests to transfuse (donate) some blood to you (so you do not pass out or DIE), while you are both waiting for help. You are blood type A and your friend has a blood type of B.

Should you accept your friend’s generous offer? Take a minute and discuss with a partner

Blood TransfusionsBlood TransfusionsIf you went ahead with the blood

transfusion. Your anti-B antibodies would react with the B antigens from your friend’s blood. Causing the red blood cells to burst and/or clump together and block vessels.

Incorrect transfusions can be fatal!

Test Your Understanding of blood Test Your Understanding of blood groups by completing the table groups by completing the table below:below:

With a partner take 2 minutes to complete the table

What blood type would be considered the universal donor?

What blood type would be considered the universal recipient?

Therefore, blood type AB are universal recipients

Blood type O are universal donors!

Practice ProblemPractice ProblemFrom our earlier problem, what

percentage of the mother’s children would be able to donate blood to her?

What about the father?

SummarySummaryBlood type is controlled for by one

gene and the interactions between 3 alleles

Blood type refers to the antigen present on the membrane of red blood cells.

Your body produces antibodies to antigens, not present inside of you. These antibodies clot red blood cells.