Welcome to Class

1. Welcome to Class Cross a homozygous dominant green plant with a heterozygous green plant. What are the genotypic and phenotypic ratios.

2. Agenda • Complex patterns of inheritance • Incomplete and Co-dominance

3. Incomplete Dominance • Organism is heterozygous its phenotype will show the dominant trait • When red snapdragons (RR) were crossed with white snapdragons (rr) offspring were pink (Rr)

5. Incomplete Dominance • one allele for a trait is not completely dominant over the other allele • Combined phenotype (blended) R = allele for red flowers W = allele for white flowers red x white ---> pink RR x WW ---> 100% RW

6. Co-dominance • In COdominance, the "recessive" & "dominant" traits appear together in the phenotype of hybrid (heterozygous) organisms

7. Practice Set up genotypes for the phenotypes listed in each set. Remember that the "medium" trait is always be heterozygous. a) Birds can be blue, white, or white with blue-tipped feathers. b) Flowers can be white, pink, or red. c) A Hoo can have curly hair, spiked hair, or a mix of both curly and spiked. D) A Sneech can be tall, medium, or short.

8. 1. Write the genotypes for the pictured phenotypes 2. Show the cross between a star-eyed and a circle eyed. What are the phenotypes of the offspring? What are the genotypes?

9. 3. Show the cross between a circle-star eyed, and a circle eyed.How many of the offspring are circle-eyed? How many of the offspring are circle-star eyed? Write the genotypic and phenotypic ratios. 4. Show the cross between two circle-star eyed. How many of the offspring are circle-eyed? How many of the offspring are circle-star eyed? How many are star eyed?

10. Welcome In humans, straight hair (ss) and curly hair (cc) are co-dominant traits that result in hybrids that have wavy hair (sc). Cross a Straight hair female with a wavy haired male. • What are the chances of having a curly haired child? • What are the chances of having a straight hair child? • What are the chances of having a wavy hair child?

11. Agenda • Quiz • Sex Linked Traits

12. Sex Determination • Thomas Hunt Morgan – studied fruit flies in the early 1900’s

13. Sex Determination • Observed that one pair of chromosomes was different between males and females • Large one named “X” chromosome • Smaller one named “Y” chromosome • XX = female; XY = male

14. XY XX X Y X X X X XX Female XX Female X XY Male XY Male Y 50% Female; 50% Male

15. Sex Linkage • Sex Linkage: the presence of a gene on a sex chromosome (X or Y)

16. Sex Linkage • X-linked genes: genes found on the X chromosome • X chromosome carries more genes • Y-linked genes: genes found on the Y chromosome

17. Fruit Fly Eye Color • Fruit flies normally have red eyes • A few males have white eyes • Red is dominant; white is recessive

18. Welcome to Class What is sex linkage?

19. Agenda • Finish sex linked traits notes • worksheet

20. Morgan’s Fruit Fly Experiments • Red-eyed female (XRXR) x White-eyed male (XrY) XR XR XRXr XRXr RESULTS: F1 generation – all red-eyed Xr XRY XRY Y

21. Morgan’s Fruit Fly Experiments • Red-eyed female (XRXr) x Red-eyed male (XRY) XR Xr RESULTS: F2 generation – 3 red-eyed and 1 white-eyed ** all white-eyed where males…why? XRXR XRXr XR XRY XrY Y

22. Morgan’s Conclusions • Gene for eye color is carried on the X chromosome = eye color is an X-linked trait • Y chromosome does not carry a gene for eye color • Red-eyed = XRXR, XRXr , XRY • White-eyed = XrXr, XrY

23. In humans colorblindness (b) is an example of a sex-linked recessive trait. A male with colorblindness marries a female who is not colorblind but carries the (b) allele. Using a Punnett square, determine the genotypic and phenotypic probabilities for their potential offspring.

24. In fruit flies red eye color (R) is dominant to white eyes (r). In a cross between two flies, 50% of the male and 50% of the female offspring had red eyes. The other half of the males and females had white eyes. What are the phenotype, and all possible genotypes, of the offspring?

25. Welcome to Class In fruit flies red eye color (R) is dominant to white eyes (r). Cross a heterozygous female with a white eye male. What are the phenotypic and genotypic ratios?

26. Agenda • Review Sex linked traits • Multiple Alleles

27. Epistasis • Epistasis – when one allele hides another • Labrador Coat Color • 2 alleles • Dominant allele E determines pigment • ee will have no pigment • Dominant allele B determines how dark the pigment • EEbb or Eebb = chocolate brown • eebb, eeBb, or eeBB will be yellow because e masks effects of dominant B allele

28. Multiple Alleles • Multiple alleles – traits that are determined by more than 2 alleles • We have only 2 alleles (1 from mom, 1 from dad) • Blood groups (ABO) • O is recessive (i allele)

30. More alleles means more combinations • there are 6 different genotypes & 4 different phenotypes for blood type • Note: 2 genotypes for both "A" & "B" blood --- either homozygous (IAIA or IBIB) or heterozygous with one recessive allele for "O" (IAi or IBi). • Note too that the only genotype for "O" blood is homozygous recessive (ii). • And lastly, what's the deal with "AB" blood?  What is this an example of?  The "A" trait & the "B" trait appear together in the phenotype.

32. Problems • A woman with Type O blood and a man who is Type AB have are expecting a child.  What are the possible blood types of the kid? • What are the possible blood types of a child who's parents are both heterozygous for "B" blood type?

33. One More • What are the chances of a woman with Type AB and a man with Type A having a child with Type O?