The A and B blood types are dominant.
Here's a breakdown of blood type inheritance:
Blood type is determined by the ABO gene, which has three common alleles: A, B, and O. Each person inherits two alleles, one from each parent. The different combinations of these alleles result in the four main blood types: A, B, AB, and O.
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Type A: Can be either AA (homozygous) or AO (heterozygous). Since A is dominant over O, only one A allele is needed to express the A blood type.
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Type B: Can be either BB (homozygous) or BO (heterozygous). Similar to type A, B is dominant over O, so only one B allele is needed to express the B blood type.
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Type AB: This individual inherits both the A and B alleles (AB). Since neither A nor B is recessive to the other, they are co-dominant. Both traits are expressed, resulting in blood type AB.
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Type O: This individual inherits two O alleles (OO). Since O is recessive, it only expresses itself when paired with another O allele.
| Blood Type | Genotype(s) |
|---|---|
| A | AA, AO |
| B | BB, BO |
| AB | AB |
| O | OO |
In summary, the A and B alleles are dominant over the O allele. When an A or B allele is paired with an O allele, the A or B blood type will be expressed. The A and B alleles are considered co-dominant when inherited together, resulting in AB blood type.
