Day 35 Co-Dominance and Blood Typing

Dihybrid Cross Quiz

Recap!

-We have learned about Mendelian traits which are either dominant or recessive

-We learned about sex-linked genes

-We learned about incomplete dominant traits

Now for Co-dominant traits

-A Co-dominant trait is the opposite of an incomplete dominant trait

-With an incomplete dominant trait the two alleles blend together

-With a co-dominant trait both alleles are expressed without any blending

Here is an example of a co-dominant trait that is also sex-linked

All Calico cats are females

Now lets talk about human blood type another good example of a co-dominant trait

For human blood type there are three different alleles

A

B

O

Both A and B alleles are co-dominant and O is recessive

-What does this mean?

If you get...

Genotype

AA= Type A blood

AO= Type A blood

AB= Type AB blood

BB= Type B blood

BO= Type B blood

OO= Type O blood

Blood type means what type of recognition protein is made by your blood cells

-A blood makes A proteins

-B blood makes B protein

-AB blood makes both A and B proteins

-O does not make any proteins

Lets practice!

Blood typing is done by adding different antigens to blood. If the antigen has an affect on the blood, the blood will clump up.

-There are two types of blood antigen

-Antigen A

-Antigen B

The way we type blood

-There is a blood typing plate that we use that has 3 wells

-You place a drop of blood in each well

-You add a drop of antigen A to one well

-If the antigen A clumps then the blood is A, if it does not clump then the blood is not A

-You add a drop of antigen B to one well

-If the antigen B clumps then the blood is B, if it does not clump then the blood is not B

-If both clump the blood is AB

-If neither clump up then the blood is O

Now lets do a blood typing lab