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Beyond Mendel

Beyond Mendel. Let’s Break Some Rules!. Incomplete Dominance: ONE ALLELE IS NOT COMPLETELY DOMINANT OVER THE OTHER; CAUSES A BLENDING OF TRAITS Codominance : BOTH ALLELES ARE DOMINANT AND SHOW UP EQUALLY IN THE PHENOTYPE; BOTH SHOW UP

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Beyond Mendel

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  1. Beyond Mendel Let’s Break Some Rules!

  2. Incomplete Dominance: ONE ALLELE IS NOT COMPLETELY DOMINANT OVER THE OTHER; CAUSES A BLENDING OF TRAITS • Codominance: BOTH ALLELES ARE DOMINANT AND SHOW UP EQUALLY IN THE PHENOTYPE; BOTH SHOW UP • Sex-Linked Traits: TRAITS THAT ARE EXPRESSED FROM A GENE LOCATED ON A SEX CHROMOSOME; ALLELES ARE CONNECTED TO THE X-CHROMOSOME OR THE Y-CHROMOSOME

  3. Incomplete Dominance: • ONE ALLELE IS NOT COMPLETELY DOMINANT OVER THE OTHER; CAUSES A BLENDING OF TRAITS • Example of Incomplete Dominance:Four o’clock flowers.

  4. Practice Problems: The petal color of four o’clocks (flowering plants) is inherited by incomplete dominance. Plants with RR genes have red flowers. Plants with WW genes have white flowers. Plants with RW genes have pink flowers. 1. Joey planted snapdragons in his garden. All the seeds came from one set of parent plants. when the flowers bloomed, Joey saw that all of his flowers were pink. What were the genes of the parent plants? Include a punnett square in your answer.

  5. 2. Kory also planted snapdragons in his garden. All of his seeds came from one set of parents. When his plants bloomed, 50% were white and 50% were pink. What were the genes of the parent plants? Include a punnett square in your answer.

  6. 3. Casie, Zach, and Kelly each have beautiful gardens of snapdragon flowers. Casie has a garden of red snapdragons and would like to create a new section to her garden including only pink four snapdragons. Zach breeds only pink snapdragons and Kelly breeds white snapdragons. From whose garden will Charmi have the greatest probability of creating a pink population of snapdragons flowers? Create two punnett squares to prove your point. Casie’s Flowers x Zach’s Flowers Casie’s Flowers x Kelly’s Flowers From whose garden will Casie choose “mates” for her flowers?

  7. Codominance: BOTH ALLELES ARE DOMINANT AND SHOW UP EQUALLY IN THE PHENOTYPE; BOTH SHOW UP • Example of Codominance: Speckled Chickens & Roan Cows • Practice Problems: • The gene for the coat color of shorthorn cattle in inherited by codominance. Red Shorthorn cattle have RR genes. White shorthorn cattle have WW genes. Roan (coat of both red and white hairs) cattle have RW genes • 1. Determine the genes of offspring of one red cow and one roan bull. Show a punnett square. What % of offspring should have red coats? white coats? roan coats? % red coats: ________ % white coats: ______ % roan coats: _______

  8. Determine the offspring of two roan parents. Show a punnett square. What percentage of offspring should have red coats? white coats? roan coats? % red coat: ________ % white coat: ______ % roan coat: _______

  9. In chickens, the allele for black feathers (B) is codominant with the allele for white feathers (W). Heterozygous chickens appear speckled with black and white feathers. A black chicken mates with a heterozygous speckled chicken. Show a punnett square. • What are the genotypic and phenotypic ratios? Genotypic Ratio: ________________________ Phenotypic Ratio: _______________________ 4. A rooster and chicken mate. When the chicks hatch 3 are speckled, 2 are black and 1 is white. What are the parents’s genotypes? Draw a punnett square to show your work. Parent’s Genotypes: ________ and ________

  10. Sex-Linked Traits: TRAITS THAT ARE EXPRESSED FROM A GENE LOCATED ON A SEX CHROMOSOME; ALLELES ARE CONNECTED TO THE X-CHROMOSOME OR THE Y-CHROMOSOME • Example of a Sex-Linked Trait: Hemophilia (blood disease) and colorblindness

  11. Practice Problems: The human blood clotting disorder is a recessive trait (must receive both recessive alleles to express trait) which is found on the X chromosome. XHXH and XHXh= females without hemophelia XhXh = female with hemophilia XHY = male without hemophilia XhY = male with hemophilia 1. A woman who is heterozygous for hemophilia mates with a male without hemophilia. What % of female offspring will be a carrier for hemophilia (heterozygous) and describe the phenotypes of the boy offspring. % female offspring carriers: ______________ male offspring phenotypes: ___________

  12. A woman who is a carrier mates with a male with hemophilia. • Will any girls have hemophilia?

  13. Below is a chart listing some alien sex-linked characteristics. Use the chart to solve the genetics problems below. • A male with yellow eyes mates with a red-eyed female. What is the chance that this couple will have a baby boy with red eyes? Probability of baby boy having red eyes: _______ % • A female, heterozygous for the body color trait mates with a pink male. What is the chance that these aliens will give birth to a purple-skinned girls? Purple-skinned Girl: _______ %

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