1. Warm-up In humans: T = ability to roll the tongue t = inability to roll the tongue E = unattached earlobes e = attached earlobes TtEE x Ttee What are the potential genotypes and phenotypes of the offspring? (yes, draw a punnett square)

2. Patterns of Inheritance 11.3

3. Incomplete Dominance One allele is not completely dominant over another allele. A heterozygous phenotype will appear as a blend of the two homozygous phenotypes. Examples: Snap Dragon Flower Color Genes may be identified in multiple ways –Red: R –White: r or R’ –Pink: Rr or RR’

4. Example White horse is crossed with a chestnut brown horse. The offspring is golden palomino. –Incomplete dominance

5. Codominance Alleles are equally dominant. A heterozygous phenotype will show both of the parental phenotypes. Exhibits both traits NOT a blend

6. Example A chicken with black feathers is crossed with a chicken with white feathers. The offspring have black and white checkers. –codominance

7. Multiple Alleles More than two alleles for a given trait –Each organism still inherits 2 alleles Example: Rabbits have 4 alleles for coat color PhenotypeAgoutiChinchillaHimalayanAlbino AlleleCC ch ChCh c Picture Dominance Dominant to all alleles Dominant to C h and c Dominant to c Recessive to all alleles Possible Genotypes C___C ch ____C h ___c___

8. Multiple Alleles More than two alleles for a given trait –Each organism still inherits 2 alleles Example: Mice have 3 alleles for coat color –C or c b – black (dominant to yellow and agouti) –c y – yellow (dominant to agouti, recessive to black) –c a - agouti (recessive to both black and yellow)

9. Example In pigeons we see three feather colors ash- red, blue, and chocolate. Ash-red B A is dominant Blue- B -is dominant to chocolate, but recessive to Ash-Red Chocolate- b -is recessive to both Ash-red and Blue What are the potential genotypes if a Blue pigeon is crossed with a Blue pigeon.

10. Sex-Linked Genes Genes located on the sex chromosomes (usually the last pair of chromosomes) Frequently found on the X (sometimes on the Y) Usually recessive Passed from Mother to son Occurs more frequently in males; less frequently in females

11. Example Eye color in fruit flies Red eye color is dominant (R) White eye color is recessive (r) Always use the sex chromosomes to notate ex. X R X R or X R X r is a female with red eyes and X r X r is a female with white eyes. What is the genotypes for males with red eyes and males with white eyes?

12. What do you see?

13. Polygenic Traits Two or more genes control the trait. Also referred to as continuous traits The result is the perception of continuous gradation in the expression of these traits. Examples: Stem height in certain plants, many human examples such as skin color, eye color etc.

14. Human examples of polygenic traits Skin colorEye colorHair color

15. Example Three genes control stem height in plants (A, B and C) For all three genes the dominant allele is tall and the recessive allele is short. Therefore AABBCC is the tallest plant and aabbcc is the shortest plant. What is the probability of getting a aabbcc genotype from parents who are heterozygous for all three genes?