When a mother with AB blood and a father with O blood have a child, the child's blood type will depend on the genetic information they inherit from their parents. Blood type is determined by the presence or absence of specific antigens (proteins) on the surface of red blood cells.
The mother has AB blood, which means that she has both A and B antigens on her red blood cells. The father has O blood, which means that he has neither A nor B antigens on his red blood cells.
The genotypes (genetic information) of the mother and father can be represented as follows:
Mother: IAIA or IAi (AB blood)
Father: ii (O blood)
The I gene determines the presence of the A or B antigens on the red blood cells. The A allele codes for the A antigen, while the B allele codes for the B antigen. The i allele codes for the absence of both antigens. The capital letters denote the dominant alleles (A and B) and the lowercase letters denote the recessive alleles (i).
When a child inherits one I allele from the mother and one i allele from the father, they will have A or B blood, depending on which I allele they inherit. When a child inherits two i alleles from both parents, they will have O blood.
Here is the calculation of the genotypic and phenotypic percentages of the possible offspring:
Genotype Phenotype Percentage
IAIA AB 50%
IAi AB 50%
ii O 50%
So, the offspring of a mother with AB blood and a father with O blood have a 50% chance of having AB blood, a 50% chance of having A or B blood, and a 50% chance of having O blood. The phenotype (observed blood type) of the offspring will depend on the combination of alleles they inherit from their parents.