Genetics Beyond Mendel Types of Dominance Genetics Beyond Mendel

Complete Dominance All of the problems we’ve studied so far One allele is completely dominant over another BB=brown hair Bb=brown hair bb=blonde hair

Heterozygous In complete dominance, the heterozygous form always expresses the dominant trait However, not all traits exhibit complete dominance

Other Types of Dominance Incomplete Dominance Codominance

Incomplete Dominance In the heterozygous form, there is a blend of traits Ex: Draw a punnett square to cross a Dark Purple flower with a White flower. PP X pp

Resulting Offspring Genotypes? Phenotypes? (physical characteristics) Pp Phenotypes? (physical characteristics) Hint: NOT Dark Purple A BLEND of Dark Purple and White… Light Purple!!!

Codominance Both traits are Dominant Heterozygous form expresses BOTH traits Ex: Cross a PP X pp Offspring: Pp, we see BOTH traits Purple and white stripes!!!

Codominance in Humans Blood Types What type are you? (don’t worry about positive or negative for now) A, B, AB, O

Types and Possible Genotypes Blood Type Possible Genotype(s) A AA, AO B BB, BO AB O OO

Which is/are dominant? Dominant: A and B Recessive O

What do the types mean?

Note for blood transfusions: Because of antibodies A can only receive type A or O B can only receive type B or O AB can receive A, B, AB or O Universal Recipient (can receive all) O can receive O only Universal Donor (can donate to all)

Codominance A woman with type A marries a man with type B. They are both heterozygous. What types of blood can their children have? Draw a Punnett Square.

Incomplete dominance Two gray bunnies (incomplete dominance) have a litter of bunnies. What are the possibilities for their offspring? Draw a Punnett Square

Jerry, Jerry, Jerry! A woman takes two possible fathers of her child to the Jerry Springer show for a paternity test. Based on their blood types, who do you think is the father? Show your work! Mom- Type A Child-Type O Dad 1- Type AB Dad 2-Type B