1. Multiple Alleles 2 2

2. Blood Type The ABO System

3. The Genetics of Blood Types
Blood type is determined by 3 alleles. This is why it is an example of multiple alleles.
Each individual can only inherit 2 of those alleles. (one from each parent)
The blood type GENE has 3 possible alleles: A, B, and O each resulting from the type of protein on the red blood cell surface.
The red blood cell protein is called an antigen 3

4. What alleles are dominant? What allele is recessive?
5) There are 6 possible combinations of these 3 alleles:
Type A: ____, _____
Type B: ____, _____
Type AB: _____
Type O: _____
What alleles are dominant?
A and B
What allele is recessive? O
Write it down!!!

5. Blood Type Shows 3 Types of Inheritance Patterns:
1) Complete dominance because…
) Co-dominance because…
) Multiple Alleles (the 3rd exception!) = _______ _______ because…
A and B alleles are dominant, O allele is recessive.
A and B alleles will hide/mask the O allele
A and B alleles are BOTH dominant.
AB blood type expresses BOTH A and B proteins (antigens) on red blood cells.
Many alleles
There are 3 possible alleles (A, B, and O) for blood type

6. AA, AO IAIA, IAi Multiple Alleles BB, BO IBIB, IBi OO ii IAIB AB
Phenotype
Genotypes
Another way of writing the alleles
Type of Inheritance Pattern Demonstrated
A type blood
B type blood
O type blood
AB type blood
AA, AO
IAIA, IAi
Multiple Alleles
BB, BO
IBIB, IBi OO ii
Codominance
IAIB AB

7. 4 Blood Types (Phenotypes)
Antigens are PROTEINS on the surface of a red blood cell.
A antigens only
B antigens only
A and B antigens
No antigens 7

8. Make sure you have it right…
proteins
Blood type

9. Antibodies are specialized PROTEINS
in the blood that attack bacteria and viruses that may infect our bodies
When antibodes “stick” they form clumps. This is called AGGLUTINATION.

10. What antibodies are present in each blood type?
Each blood type has antibodies opposite to it. For example, if a cell has A antigens, then it has anti-B antibodies. Because a B protein would be a foreign substance!

11. The shape of the antibody protein is SPECIFIC to the shape of the antigen protein!

12. Make sure you have it right…
proteins
proteins
Blood type

13. What if you get the wrong blood type in a transfusion?
Antibodies in your own blood will attack the foreign blood cell’s surface proteins/antigens.
When antibodes “stick” to an antigen they form clumps. This is called AGGLUTINATION.

14. Can you figure these out?
attack
antigens (proteins)
Can you figure these out?

15. So who can receive blood from who?
Can receive from:
So can you figure out the DONORS?
Can only receive blood with matching antigens
Can only donate if no antibodies are present

16. Make sure you have it right…

17. Interesting Information…

18. Solving Blood Type Problems
1) A mother is homozgyous for Type A blood. Her husband has Type O blood.
What are the possible phenotypes of their children?
What is the likelihood of the couple having a child with Type A blood? __________________
What is the likelihood of the couple having a child homozygous for Type A blood? _____________
Key:
Type A:
Type B:
Type AB:
Type O:
Possible
Phenotypes:
Parent 1:
Parent 2:

19. 2) A mother is homozygous for Type B blood
2) A mother is homozygous for Type B blood. She has a child with Type AB blood. What are the possible genotypes of the father?
Key: Type A: AA, AO Type B: BB, BO Type AB: AB Type O: O
Father’s Genotype(s):
Parent 1:
Parent 2:

20. 3) A mother has the genotype IAi and the father has the genotype IBi
3) A mother has the genotype IAi and the father has the genotype IBi. What are the chances they will have a child with Type O blood?
Key:
Type A:
Type B:
Type AB:
Type O:
Answer:
Parent 1:
Parent 2:

21. Quick Video to put it all together
Amoeba Sisters!
Multiple Alleles (ABO Blood Types) and Punnett Squares
Complete the worksheet while you watch.

24. Practice Time! Work through the “Who’s Your Daddy??” practice sheet.
Check your answers at the SSS!