2. Variations on Mendel

3. 1. INCOMPLETE DOMINANCE Neither trait is completely dominant over the other Get a BLEND of the two traits The new phenotype is somewhere between the original two

4. I W = white I R = Red White Carnation x Red Carnation Parent Genotypes? –I W I W x I R I R –Do the Punnett Square What do you get????

5. IWIW IWIW IRIR IRIR I W I R I W I R = 4 / 4 are pink carnations

6. What happens if you cross 2 Pink Carnations? –I W I R x I W I R –Do the Punnett Square –What phenotypes occur?

7. IWIW IRIR IWIW IRIR I W I W I R I R I W I W = 1 / 4 white I W I R = 2 / 4 pink I R I R = 1 / 4 red

8. Another Incomplete Dominance example….. White bunny x brown bunny = ?? I W I W x I B I B = I W I B I W I B = tan IWIBIWIB IWIBIWIB IWIBIWIB IWIBIWIB I W I W IBIBIBIB

9. 2. CODOMINANCE Two traits are dominant at the same time Both traits are fully expressed at the same time

10. EX: Speckled Chickens These birds have BOTH black and white feathers Both black and white are dominant

11. I B I B = black feathers I W I W = white feathers I B I W = speckled Cross a black with a speckled- -what are possible phenotypes?

12. IBIB IBIB IBIB IWIW I B I B I W I B I B = 2 / 4 black I B I W = 2 / 4 speckled

13. Blood Type: based on 2 gene groups (1)ABO: --Two dominant ( I A and I B ) --One recessive ( i ) –I A I B makes ______ –I A i or I A I A makes ______ –I B i or I B I B makes _______ – i i makes _______

14. Can a Type A and a Type B have: –Type AB child? Yes –Type A child? Yes..if Type B parent is I B i –Type B child? Yes…. if Type A parent is I A i –Type O child? Yes…if both are heterozygous

15. Blood Type: based on 2 groups of genes (2) Rh Factor: -- One dominant gene ( I +) -- One recessive gene ( I - ) I A i I + I - makes _________ I B i I + I - makes __________ i i I - I - makes __________

16. 5. Sex-Linked Genes X & Y = sex chromosomes X X = female genotype X Y: male genotype “X” –carries traits –Colorblindness, hemophilia “Y” --no corresponding traits Males are more likely to have these recessive traits than females

17. 5. Sex-Linked Genes X B = normal sight X b = colorblind Colorblind Female = X b X b Normal Female= X B X B or X B X b Colorblind Male= X b Y Normal Male = X B Y