Each person can have one of four possible blood types: A, B, AB, or O....
Each person can have one of four possible blood types: A, B, AB, or O. Blood type A means that the A antigen is present on the red blood cell surface. Blood type B means that the B antigen is present on red blood cells' surfaces. Blood type AB means that both the A antigen and the B antigen are present on the red blood cells' surfaces. Blood type O means that no antigens are present on the red blood cells' surfaces. A mother with blood type A and the genotype A/O and a father with blood type B and genotype B/B have a child with blood type AB. This is an example of what type of inheritance pattern?
- A. X-linked autosomal dominance
- B. Incomplete dominance
- C. Codominance
- D. Complete autosomal dominance
Correct Answer: C. Codominance
Explanation
The child is blood type AB, meaning that the child has both the A antigen and the B antigen on his or her red blood cells. The child is able to express the products of both genes simultaneously. The A antigen was inherited from mom, and the B antigen was inherited from dad. The A and B alleles are codominant because they can both be expressed in the same person at the same time if the person inherits both alleles, as is the case in this example.