Expert: Walter Hintz - 8/28/2009

Question
I have answered a question about possible blood types for a parent with type A and one with type B.  I came up with a 25%chance of type A, AB, B, or O.  Is there any other possible combinations and what percent do they occur?

Answer
You have used only phenotypes and not genotypes. Yjr phenoype is what you can see by typing and the genotype is what genes are present. There are paired genes for each trait. For example Is one parent AA or AO ( both phenotypes would be A)  and is the other BB or BO (both  phenotypes would be B)
If you had this cross   AO   x   BO you would be correct 25% each  BUT
  If this was the cross   AA    x   BB  100%  would be AB
   If the cross was   AO    x   BB  1/2 would be AB and 1/2  B
   If AA    x  BO   1/2 would be AB and 1/2 would be B

If you do not uderstand this let me know