1. Other Types of Genetic Crosses And their Punnett Squares

2. Multiple Alleles Wild Type Red Eyes Mutant White EyesMutant Honey Eyes Mutant Apricot Eyes Example: Fruit fly eye colour

3. Multiple Alleles More than 2 alleles for a gene. More than 2 alleles for a gene. Dominance hierarchy. (One will dominate over others.) Dominance hierarchy. (One will dominate over others.) Show this in solution using the first letter of the gene name, then a superscript to reflect how dominant it is (1 is most dominant) Show this in solution using the first letter of the gene name, then a superscript to reflect how dominant it is (1 is most dominant)

4. Multiple Alleles Example: Fruit Fly eye colour (memorize this for test) Example: Fruit Fly eye colour (memorize this for test) –4 alleles:  Red, Apricot, Honey, White –Each allele shows some dominance, except White (E 4 ):  Red (E 1 ): Dominant to all (E 1 E 1, E 1 E2, E 1 E3, E 1 E4)  Apricot (E 2 ): Dominant over honey & white (E 2 E 2, E 2 E 3, E 2 E 4 )  Honey (E 3 ): Dominant over white (E 3 E 3, E 3 E 4 )

5. Codominance Example: Coat colour in horses

6. Codominance Both alleles show up in hybrid. Both alleles show up in hybrid. –Example: Some hairs are brown, some are white. There is NO dominant allele. There is NO dominant allele. Show this in Punnett Squares using the first letter of the gene word, and Superscripts – the first letter of the trait word. Show this in Punnett Squares using the first letter of the gene word, and Superscripts – the first letter of the trait word.

7. Codominance Example: A chestnut (red) horse and a white horse are crossed. All the offspring are roan (both red and white hairs). Example: A chestnut (red) horse and a white horse are crossed. All the offspring are roan (both red and white hairs). Let C R = RedC W = White Red horse: C R C R White horse: C W C W CRCR CRCR CWCW CWCW CRCWCRCW CRCWCRCW CRCWCRCW CRCWCRCW

8. Incomplete Dominance Example: Colour of flowers in snapdragons

9. Incomplete Dominance The alleles blend to form a different heterozygous phenotype. The alleles blend to form a different heterozygous phenotype. –Example: Having a red allele and a white allele will make the flower pink. We show this in a Punnett Square the same way as with Codominance. We show this in a Punnett Square the same way as with Codominance.

10. Incomplete Dominance Example: Purebred red snapdragons crossed with purebred white snapdragons produced pink snapdragons. Example: Purebred red snapdragons crossed with purebred white snapdragons produced pink snapdragons. Let C R = RedC W = White Red snapdragon: C R C R White snapdragon: C W C W CRCR CRCR CWCW CWCW CRCWCRCW CRCWCRCW CRCWCRCW CRCWCRCW

11. ABO Blood Groups Four possible blood types: A, B, AB, and O. Four possible blood types: A, B, AB, and O. Both multiple alleles and codominance. Both multiple alleles and codominance. –“A” allele (I A ) codes for galactosamine on blood cell membrane (allows your body to recognize it as its own) –“B” allele (I B ) codes for galactose –“O” allele (i) codes for neither Both I A and I B are dominant over i, but neither is dominant over the other Both I A and I B are dominant over i, but neither is dominant over the other –I A I B : both galactosamine and galactose are expressed

12. Phenotypes: Genotypes A blood type: I A I A, I A i A blood type: I A I A, I A i B blood type: I B I B, I B i B blood type: I B I B, I B i O blood type: ii O blood type: ii AB blood type: I A I B AB blood type: I A I B

13. Donating & Receiving Blood Giving blood: Giving blood: –O gives to everyone –A can give to A and AB –B can give to B and AB –AB can give to AB Getting blood: Getting blood: –AB can get blood from anyone –A can get blood from A or O –B can get blood from B or O –O can only get blood from O