Inheritance of ABO Blood Groups

Definition

Gene that exists in more than 2 different forms is said to have multiple alleles. #BiologyDefinitions

Individual can only have 2 alleles → 1 allele from each parent. With multiple alleles → can be diff. combinations of 2 alleles.

• makes it possible to have more than 2 phenotypes expressed based on the dominant or recessive alleles available in the trait.

Gene for human blood group → is example of gene with multiple alleles.

4 blood groups in human populations (A, B, AB, O) Human Transport System Main Note Alleles for blood group A B O are: $I^A,I^B,I^O$. $I^A$ and $I^B$ are dominant over $I^O$ → but $I^A$ and $I^B$ exhibit codominance.

Therefore individuals with alleles $I^A$ and $I^B$ will have blood group AB.

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