Mendel is the father of modern genetics however there are some genetic characteristics that cannot be describeed by simple Mendelian genetics. Such is the case by the human blood types in which there are three alleles for the same gene, A B and o. A parent is able to pass allele A, B or o to the offspring based on the parent's genotype.
From these three 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 instance of codominance in which both A and B alleles are codominant to each other.
Blood types is able to be used in forensics to determine if blood is from the victim or criminal. Blood types is able to be used to determine parental source in situation where the father is unknown, but blood types can only eliminate certain blood types. DNA fingerprinting is a better method which is used often in criminal and parental determination cases.
Punnett squares such as the one shown above are used to determine the likelihoods (percentages) for genotypes of offspring given specific genotypes for the parents.
1. In the illustration above the Punnett Square represents a cross (mating) among a male (on the left side) with blood type AB and a female, (top of square), with blood type A, genotype Ao.
Answer the subsequent for the cross represented above.
1. describe what are the possible blood types for the offspring?
2. describe what are the ratios or percentages for each possible blood type from this cross?
3. describe what blood type is not possible from this cross?
1. Fill out two Punnett squares for a cross among 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 as well as answer the following problems about them.
1. What are the probable blood types for the cross between the type B (BB or Bo?) male and AB female?
2. What are the percentages (%) or possibilities for each blood type in the offspring? What blood type(s) wouldn't be possible in a cross between these two parents?