HW: Co-dominance Practice Tuesday April 4, 2017 I can: predict offspring ratios for co-dominant traits Agenda (10) Catalyst (25) GN and Board Work: Co-dominance and Blood Types (40) Who’s the Daddy? Genetics (10) Co-dominance Practice Catalyst How many phenotypes do you see in incomplete dominance? How does the heterozygote compare to the homozygotes? Show all steps. Blue beetles and yellow beetles mate to produce green beetles. What is the likely outcome of a cross between a green beetle and a blue one? HW: Co-dominance Practice

Exit Ticket Review B b B BB Bb b Bb bb 1. In mice, a certain species displays incomplete dominance in coat coloring. The offspring of a black (BB) mouse and a white (bb) mouse are gray (Bb) mice. A cross between two gray mice will most likely produce offspring with which percent of coat colors? A. 25% black, 75% gray B. 25% gray, 75% white C. 25% white, 25% black, 50% gray D. 25% gray, 25% black, 50% white Draw a completed Punnett Square for the problem above. B b B BB Bb b Bb bb

Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes. complete dominance incomplete dominance co-dominance multiple alleles sex-linked

Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.

B = black W = white white black WW BB BW Co-dominance is a pattern of inheritance in which both dominant alleles contribute to the phenotype. The heterozygous phenotype shows both traits. When there are two dominant alleles in one genotype, both are expressed. B = black W = white erminette (black AND white) white black WW BB BW

red cow + white cow = roan cow (red and white)

? BB black B = black W = white Coat color in mice exhibits co-dominance. ? BB black

? WW white B = black W = white Coat color in mice exhibits incomplete dominance. ? WW white

? BW checkered B = black W = white (black and white) Coat color in mice exhibits co-dominance. ? BW checkered (black and white)

R = red B = blue Flowers exhibit co-dominance for petal color. ? RR red

R = red B = blue Flowers exhibit co-dominance for petal color. ? BB blue

? RB red and blue R = red B = blue Flowers exhibit co-dominance for petal color. ? RB red and blue

R = red W = white Cow coat color follows a pattern of co-dominance. ? RR red

R = red W = white Cow coat color follows a pattern of co-dominance. ? WW white

R = red W = white Cow coat color follows a pattern of co-dominance. ? RW roan

Solving a Co-dominance Problem The two alleles for fish scale color, red and yellow, are co-dominant. If a red fish mates with a speckled red-and-yellow fish, what percentage of their offspring will be yellow? Y = yellow; R = red Solving a Co-dominance Problem R R 1. Read the problem. Underline the known alleles. Identify the type of inheritance as co-dominance. R R R R R 2. Choose a letter to represent each allele in the problem. 3. Circle and/or write down the genotypes of the parents. R R Y 4. Set up and solve Punnett Square. Y Y 5. Highlight and answer what the question is asking. parents: RR x RY yellow = 0/4 = 0%

What type of inheritance? (Complete, Incomplete, or Co-Dominance) Red flowers are crossed with white flowers. All the flowers produced are red. How do you know what type of inheritance it is?

What type of inheritance? (Complete, Incomplete, or Co-Dominance) Red flowers are crossed with white flowers. All the flowers produced are pink. How do you know what type of inheritance it is?

What type of inheritance? (Complete, Incomplete, or Co-Dominance) Red flowers are crossed with white flowers. All the flowers produced are speckled red-and-white. How do you know what type of inheritance it is?

What type of inheritance? (Complete, Incomplete, or Co-Dominance) A black cat mates with a white cat. All of their children are white with black spots. How do you know what type of inheritance it is?

What type of inheritance? (Complete, Incomplete, or Co-Dominance) A red flower is crossed with a yellow flower. All of the flowers produced are orange. How do you know what type of inheritance it is?

What type of inheritance? (Complete, Incomplete, or Co-Dominance) A red flower is crossed with a yellow flower. All of the flowers produced are red-and-yellow. How do you know what type of inheritance it is?

An important example of co-dominance AND multiple alleles is human blood groups. The proteins on the surface of red blood cells determine your blood type, and those are determined by genes. both A and B proteins are expressed = codominance!

IA = type A (dominant) IB = type B (dominant) i = type O (recessive) Human blood type is determined by 3 alleles (2 dominant, 1 recessive): Just like with any other trait, you must have two alleles for blood type. You still inherit one allele from each parent. IA = type A (dominant) IB = type B (dominant) i = type O (recessive) phenotypes: IAIA or IAi IBIB or IBi IAIB ii genotypes:

What’s the blood type? ii type O

What’s the blood type? IAi type A

What’s the blood type? IAIB type AB

What’s the blood type? IBIB type B

What’s the blood type? IAIA type A

What’s the blood type? IBi type B

Write the genotype for the phenotype described: heterozygous type A IAi

Write the genotype for the phenotype described: homozygous type B IBIB

Write the genotype for the phenotype described: homozygous type A IAIA

Write the genotype for the phenotype described: heterozygous type B IBi

Write the genotype for the phenotype described: type O ii

Write the genotype for the phenotype described: type AB IAIB

Write the genotype(s) for the phenotype described: type A IAIA or IAi

Write the genotype(s) for the phenotype described: type B IBIB or IBi

Solving Blood Type Problems A woman who is heterozygous for blood type B has a child with a man with heterozygous type A blood. What are the possible genotypes of their children?