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Codominance

Codominance. When there are at least 2 usually 3 alleles that influence a trait. 1 is recessive. The other 2 are dominant to that allele but not to each other. Human Blood Types. In the human population, there are 3 major alleles for the surface protein gene: A, B, and O. A.

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Codominance

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  1. Codominance When there are at least 2 usually 3 alleles that influence a trait. 1 is recessive. The other 2 are dominant to that allele but not to each other.

  2. Human Blood Types In the human population, there are 3 major alleles for the surface protein gene: A, B, and O. A A and B are dominant to O but not to each other B O Recessive

  3. Human Blood Types

  4. IB IB IAIB IAIB IA 1/2 = IAIB 1/2 = IBi i IBi IBi Codominance • Example: homozygous male B (IBIB) x heterozygous female A (IAi)

  5. IA IB IAi IBi i 1/2 = IAi 1/2 = IBi i IAi IBi Codominance • Example:male O (ii) x female AB (IAIB)

  6. Codominance • In codominance, the alleles are neither dominant, nor recessive. Neither allele is masked by the other. Roan Cow Is both white and red

  7. Chestnut or Red Roan

  8. Black or Blue Roan

  9. Palonimo

  10. Mystery Bull Experiment • http://tepserver.ucsd.edu/people/Tracee-Parsons/Final-genetics-project/mystery-bull.html

  11. Flav-R-Gro, Inc. • Through genetic engineering, you and your partner, Maisie have developed a new type of corn. You have named it WonderCorn. • It has a tasty flavor of butter and salt. • The good thing about this new corn is that you do not have to add butter and salt to it once it is cooked. • This makes it a much healthier dish.

  12. You and Maisie suspect that the taste trait is corn in codominant. To find out, you crossed two other types of corn: a homozygous salty corn (SS) and a homozygous buttery corn (BB). The offspring were all WonderCorn. Create the Punnett Square

  13. S S B SB SB B SB SB What is the genotype of WonderCorn? What percent of the offspring will have this genotype?

  14. You were correct. Taste is a codominant trait. Make a Punnett Square showing a second-generation cross. (Both parents are heterozygous) What percent of the offspring will be WonderCorn? S B S SS SB B SB BB 50 % will be WonderCorn. 1:2:1 Ratio

  15. The demand for WonderCorn is high. Grover’s Grocery has already ordered 50 bushels and wants more. You are all out. You are at the beginning of a new growing season. Would you be better off using homozygous plants to grow or heterozygous? Why? Yummy to my tummy!

  16. If a heterozygous cross produces 736 offspring, how many will be WonderCorn? How many of the 736 offspring will taste salty but not buttery? Do the math! 50% of 736 = 368 25% of 736 = 184

  17. Quiz Tomorrow

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