1. Multiple Alleles
Human Blood Types

2. Multiple allele traits: controlled by three or more alleles of the same gene that code for a specific trait.
ex. Human Blood Types: ABO

4. ABO System
A. 4 possible blood types A, B, AB, O
1. Type A: has A antigen on red blood cells (RBC), has anti-B antibodies, can get blood from O and A, can give blood to A and AB people

5. 2. Blood type B: has B antigen on RBCs, anti-A antibody, can get blood from O or B, can give blood to B and AB
3. Blood type AB: has both A and B antigens on RBCs, no antibodies, can get blood from A, B, AB, and O, can give blood to AB

6. 4. Blood type O: has no antigens on RBCs, has both anti-A and anti-B antibodies, can get blood from O only, can give blood to A, B, AB, and O

7. Genotypes for human blood type