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Heredity not following the Rules

Explore concepts like incomplete dominance, codominance, and polygenic inheritance with examples like snapdragons, Dominique chickens, and blood typing. Practice Punnet Squares and genetic crosses to deepen your understanding.

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Heredity not following the Rules

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  1. Heredity not following the Rules Non-Mendelian Genetics

  2. Incomplete dominance • A heterozygous condition in which both alleles are partially expressed, often producing an intermediate or blended phenotype (which is different than either of the homozygous forms). Snapdragons

  3. Incomplete dominance • Both traits are "weak" and not strong enough alone, so they blend their strengths to make a new color. Snapdragons

  4. In Incomplete DOMINANCE, use the SAME letters since they both are weak! Incomplete dominance RR rr Rr RR Rr Rr rr

  5. Incomplete dominance • Palomino horses are a cross between a chestnut horse and a cremello (white) color horse. • Practice the cross using a Punnet Square. H’ H’ H H

  6. Codominance • Codominance –Neither phenotype is recessive. Instead, the individual expresses both phenotypes. Co – both are dominant enough to be expressed!! Dominique chickens

  7. In CODOMINANCE, use DIFFERENT letters since they both are strong! Codominance BB - Black WW - White BW - Black and White W W Predict the outcome if BOTH chickens are dominique (black and white) ???? Cross a black chicken with a white chicken and what to you get if the traits are CODOMINANT? B B

  8. Codominance BB - Black WW - White BW - Black and White B W BB=1 B BW=2 W WW=1

  9. Codominance • Another example of codominance is ABO blood typing. The blood types A and B are codominant to each other; however, type O is actually recessive to A and B.

  10. Codominance BB or BO OO AB AA or AO When both alleles exist, both are present!

  11. Practicing Blood Types • A man of blood type AA marries a woman with blood type AB. What is the chance they will have a child with type AB blood? A B A A AB?

  12. More Practice What is the expected genotypic ratio among children born to a mother having the genotype IAiO and a father with the phenotype AB?

  13. Polygenic Inheritance • Polygenic inheritance is the inheritance pattern of a trait that is controlled by two or more genes. The genes may be on the same chromosome or on different chromosomes. • Height in humans • Skin color

  14. POPQUIZ!! (Just kidding) • A roan cow is the product of a red bull and a white cow. What type of inheritance is exhibited? • Complete dominance • Codominance • Incomplete dominance • Sex-linked • Multiple alleles • Polygenic • B

  15. POPQUIZ!! • Curly hair people have the genotype HH, while people with straight hair have the genotype hh. A person with wavy hair is heterozygous. What type of inheritance does this exhibit? • Complete dominance • Codominance • Incomplete dominance • Sex-linked • Multiple alleles • Polygenic • C

  16. POPQUIZ!! • Hair loss is a trait caused by a gene located on the X chromosome. This trait would be considered - • Complete dominance • Codominance • Incomplete dominance • Sex-linked • Multiple alleles • Polygenic • D

  17. POPQUIZ!! • Kim’s has always wondered why her 2nd toe is longer than her first. She recently discovered that it is a dominant trait. This trait is considered to exhibit - • Complete dominance • Codominance • Incomplete dominance • Sex-linked • Multiple alleles • Polygenic • A

  18. POPQUIZ!! One parent has the blood type A and the other blood type B. What are the genotypes of the parents if they produce children with only blood type AB?

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