Heredity not following the Rules

1. Heredity not following the Rules Non-Mendelian Genetics

3. 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

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

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

6. 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

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

8. 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

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

10. 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.

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

12. 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?

13. 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?

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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?