Codominance, Incomplete Dominance, and Multiple Alleles! Name Block Date Let s try our luck at some problems involving codominance and incomplete dominance! Remember that codominance is when we see 2 alleles expressed at the same time individually in the phenotype. Incomplete dominance is the blending of the two alleles as a phenotype. Codominance * Birds can be blue, white, or white with blue-tipped feathers. * Use these Letters: Blue = C B White = C W What would the genotype be for each of the combinations listed above? Blue White with blue-tips White Let s do a punnett square to figure out what would result from a cross between a White bird and a White with blue-tipped feathered bird. Write the cross and do the punnett square! Cross: X What are the possible genotypes? What are the possible phenotypes? What is the probability they will have a Blue offspring?
Let s do one more! What would be the result if we crossed a White bird with a Blue bird? Set up the cross and answer the questions. Cross: X What are the possible genotypes? What are the possible phenotypes? What is the probability they will have a Blue offspring? Here s a different scenario! Let s look at some flowers! Flowers can be white, pink, or red. Please use these letters: White = C W Red = C R What would the genotypes be for each of the following phenotypes? White Pink Red What would the cross be between two Pink flowering plants? Write the cross and do the punnett square! Cross X What are the possible genotypes? What are the possible phenotypes? What is the probability they will have a White offspring?
Incomplete dominance Look at the examples for the Sneeches! Pay close attention to the letters used to represent the alleles and use those letters to answer the punnett squares and questions. A Sneech can be tall, medium, or short. The alleles you will use for height are: H = tall h = short What would the genotype be for: Tall Medium Short Try this! Two medium height Sneeches are trying to figure out what the odds of them having a tall offspring would be. Set up the cross and tell what the potential outcome would be for them! Cross: X What are the possible genotypes? What are the possible phenotypes? What is the probability they will have a tall offspring? Continue to next page...
In Smileys, eye shape can be starred, circular, or a circle with a star. Write the genotypes for the pictured phenotypes Use these letters: Circle = E Star = e Genotype: Show the cross between a star-eyed and a circle eyed. Cross; X What are the phenotypes of the offspring? What are the genotypes? Show the cross between two circle-star eyed. Cross X How many of the offspring are circle-eyed? How many of the offspring are circle-star eyed? How many are star eyed?
Genetics: Multiple Allele Traits Blood Type Blood type is controlled by 3 alleles: A, B, O. A & B are codominant, O is recessive. 1. a) What are the two genotypes possible for a person who as A blood? b) What genotype does a person with AB blood have? c ) What genotype does a person with O blood have? d) What are the two genotypes possible for a person who as B blood? 2. A man with type AB blood is married to a woman also with type AB blood. What percentage of their children will have: A blood? B blood? O blood AB blood Show your work: 3. A man has type B blood (genotype BB) is married to a woman with type O blood. What blood type will all their children have? What is the genotype of the children? Show your work: Continue to next page...
5. A woman with type A blood is claiming that a man with type AB blood is the father of her child who is type B. Could this man be the father of the child? Show the possible crosses; remember that the woman can have AA or AO genotypes. Assuming that he is the father, what must the mother's genotype be? 6. A man with type AB blood is married to a woman with type O blood. They have two natural children and one adopted child. Jane has type A blood, Bobby has type B blood, and Grace has type O blood. Which child was adopted? Show your work to provide support for your answer!