2. Extending Mendel Genetics: Other Genetic Variations: Dominance variations - complete, incomplete, codominance Polygenetic & Multiple Alleles Pleiotropy Epistasis

3. Codominance Both alleles can be expressed For example, red cows crossed with white will generate roan cows. Roan refers to cows that have red coats with white blotches. (RW) Questions: 1. What is this type of inheritance called? 2. Why is is called that? 3. What genotype is used to depict a red cow, white cow, and a roan cow? Tasks: 1. Using a Punnett Square, mate a red bull with a white cow, to determine the F 1 generation’s genotype and phenotype. 2. Determine the F 2 generation: a. Genotypes b. Phenotypes

4. Incomplete Dominance In some cases, an intermediate phenotype is shown Neither allele is dominant In Snapdragons, flower color can be red, pink, or white. The heterozygous condition results in pink flowers (or an intermediate trait) R1R1R1R1 R2R2R2R2 R1R2R1R2 Questions: 1. Why is this considered Incomplete Dominance? 2. The trait you’re looking at is? 3. What are the three alleles for Snapdragon flower color? Tasks: 1. Cross a white Snapdragon with a red Snapdragon and determine the genotype and phenotype ratios of the F 1 generation. 2. Cross two pink Snapdragons and determine the genotype and phenotype ratios of the F 2 generation. 3. Cross a red Snapdragon with a pink Snapdragon and determine the genotype and phenotype ratios of the F 3 generation.

5. Multiple Alleles (& codominance): Blood Types ___________ Type B Blood Type AB Blood Type O Blood Type A Blood I B I B or I B i IAIBIAIB ii I A I A or I A i 10% 4% 46% 40% Blood Test Phenotype Genotype Population

6. If a dad is heterozygous for Type B blood and a mom is heterozygous for Type A blood… Create a Punnett Square to determine the blood types of their children. If a dad is heterozygous for Type B blood and a mom is heterozygous for Type A blood… Create a Punnett Square to determine the blood types of their children. IBIB i IAIA i IAIBIAIB IAiIAi I B ii ii i 1. What are the blood types of the children? 2. Which child(ren) can the mom donate to? 3. Which child(ren) can the dad donate to? 4. Who can get blood from everyone in the family (the universal recipient)? 5. Who can donate blood to everyone in the family (the universal donor)? 6. Who in the family cannot get blood from any family member? Why? Blood Typing

7. Sickle Cell and Codominance Homozygous for normal hemoglobin allele (HBA) receive a normal hemoglobin allele from each parent and do not have any sickled RBC’s: AA Homozygous for mutant or sickle cell hemoglobin allele (HBS) receive a Sickle cell allele from each parent and are said to have sickle cell disease: SS, Resulting in abnormal, sickle-shaped RBC’s. Heterozygous receive one normal hemoglobin allele (A) and one mutant or sickle cell allele (S) = AS and they do manifest some sickling in low-oxygen environments. http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html Heterozygous Advantage The protozoan that causes Malaria (and it deposited via mosquitos) has an affinity to sickled cells and starts its life cycle in those cells rather than the normal RBC’s, but sickled cells are short-lived 10-20 days and die before the protozoan’s life cycle is complete, thus eradicating the disease.

8. Pleiotropy (resulting in multiple seemingly unrelated effects) in Sickle Cell Disease

9. 1. Sickle Cell Anemia is a genetic disorder caused by one wrong DNA base, CAT instead of CTT, making amino acid ______ rather than ________ This called a _______ mutation. 2. Why are people who are heterozygous for sickle cell generally healthy? ________________________________________ 3. What disease are people who carry the sickle cell trait immune to (heterozygous advantage) ? _________ (which is caused by a protozoan parasite passed on by a ________) Because they have enough red blood cells that are not sickled and can adequately carry oxygen. Malaria mosquito Point Val Glu

10. Pigments (displaying Multiple Alleles) = Polygenetics i.e. skin, eyes, hair GeneTree Eye Color Inheritance Chart: 01233-4456 In anatomy, heterochromia refers to a difference in coloration usually of the iris, but also of hair & skin. Eye color is determined primarily by the concentration and distribution of melanin (a pigment). Heterochromia is a result of the relative excess or lack of Melanin, due to genetics, mosaicism, disease or injury. Blue & Green Brown & Hazel Crossing over during mitosis can cause mosaicism

11. Colorblindness Hemophilia Hairy Ear Red-Green color blindness = sex (X) linked Trichromats - blue/yellow color blindness is not sex-linked, rather it’s autosomal, on the 7th chromosome) Hemophilia - x-linked Hairy Ears - y-linked

12. Polygenic In cats, the gene that controls the color of coat spots is located on the X-Chromosome – expressing (or not) either black or orange or possibly both if there are 2 X chromosomes. Calico cats are white with patches of black & orange. Tortoiseshell cats are black & orange with sparse to no patches of white. These conditions happens because one X chromosome may have the allele for gold patches, while the other X may have the allele for black patches. Since females have 2 X chromosomes, they can have two different color patches. If you see a cat with 3 colors: white black, and orange, it’s almost certain it’s a female. What condition in humans would give a male XXY?

13. Multiple Alleles & Polygenetic Labrador Retriever Genetics Black is dominant (B) to chocolate (b) Yellow is (ee) recessive epistatic (when present, it blocks the expression of the black and chocolate alleles) GenotypePhenotype BBEE BbEE BBEe BbEe bbEE bbEe BBee Bbee bbee Questions: 1. What in the genotype is unique to the yellow lab? 2. What does epistatic mean? 3. What color lab would you expect with BB or Bb? And with bb? Task: Determine the number of black, chocolate, and yellow labs produced from a black female and a yellow male. (BbEe x bbee) Hint: Set it up like a two trait Punnett Square (16 offspring)

14. Drosophila fruit fly lab Students enter as a guest. http://sciencecourseware.org/vcise/drosophila/ 1. Order a wild type (red-eyed) female and mate it with a white-eyed vestigial wing size male, 2. View shopping cart and check out 3. Go to the lab - observe F 1 generation (record the phenotypes, genders, # ’ s) 4. Create an F2 generation with the F1 flies (record the phenotypes, genders, # ’ s) 5. Take the quiz