Mendel is the father of the modern genetics; however there are some genetic characteristics which can’t be described by simple Mendelian genetics. Such is the case with human blood types in which there are 3 alleles for the similar gene, A B, and o. A parent can pass allele A, B, or o to the offspring based on parent's genotype.
From such 3 alleles, there are 4 blood types (phenotypes): A, B, AB, and O and there are six genotypes: AA, Ao, BB, Bo, AB or oo. This is an illustration of codominance in which both A and B alleles are codominant to one other.
Blood types can be employed in forensics to find out if blood is from the victim or criminal. Blood types can be employed to find out parental source in condition where the father is unknown; though, blood types can only remove certain blood types. DNA fingerprinting is a better technique which is used frequently in criminal and parental determination cases.
Punnett squares like the one shown above are employed to find out the probabilities (percentages) for genotypes of offspring given particular genotypes for parents.
Part A: In the illustration above, the Punnett Square represents a cross (that is, mating) between a male (on the left side) with blood type AB and a female, (top of square), with blood type A, genotype Ao. Illustrate the possible blood types for offspring?
Answer the given for cross represented above.
a) Illustrate the possible blood types for offspring?
b) Illustrate the ratios or percentages for each possible blood type from this cross?
c) Name the blood type which is not possible from this cross?
Part B: Fill out two Punnett squares for cross between a male with blood type B and a female with blood type AB. (Note that we don’t know if the father is genotype BB or Bo from the information given. Therefore there are two solutions to the possible cross.)
Set up two Punnett squares and answer the given problems regarding them.
a) Illustrate the possible blood types for the cross between the type B (BB or Bo?) male and AB female?
b) Illustrate the percentages (%) or probabilities for each and every blood type in the offspring?
c) What blood types would not be likely in a cross between such two parents?