1. Alternate Patterns of Inheritance

2. The simple rules of Mendelian inheritance (complete dominanance) do not always apply…. there are exceptions

3. 1. Co-Dominance  BOTH alleles are dominant  In a heterozygous individual, BOTH are expressed in original form  Results in having characteristics of BOTH parents

4. Co dominance  Example  Red flowers + white flowers  red/white flowers

5. Co dominance  Examples in humans:  Blood types  Sickle Cell Anemia

6. 2. Incomplete Dominance  NEITHER allele is dominant (equal)  In a heterozygous individual NEITHER original trait can be seen  Results in a combined phenotype, or blend

7. Incomplete dominance  Example  Red flowers + white flowers  pink flowers  Example in humans: Skin color

8. 3. Sex-linked traits  Sex-linked gene is located on the X chromosome  The X chromosome is longer and has more genes than y  Therefore, sex-linked traits are always x- linked

9. X-linked traits  Result  Females will have 2 copies of the sex-linked trait  Males only have one copy of this gene  Even if the gene is recessive, males only need one gene to get the trait  Therefore males exhibit some traits more frequently than females

10. Example of x-linked traits  HEMOPHILIA  Recessive disorder  Missing a trait that codes for a protein essential to blood clotting  Bleeders disease – bleed very easily  Females can get the disease, but usually act as a carrier (have the gene/not the disorder)

11. HEMOPHILIA  PHENOTYPE Normal female Female carrier Hemophiliac female Normal male Hemophiliac male  GENOTYPE XXXXXXXX Xh XXh XXh XXh X Xh XhXh XhXh XhXh Xh XY XY XY XY XhYXhYXhYXhY

13. Other examples of x-linked   BALDNESS   Red/Green Color blindness   Color vision testColor vision test

14. Genetics Vocabulary 1. dominant 2. recessive 3. genotype 4. phenotype 5. allele 6. homozygous 7.heterozygous 8. incomplete dominance 9. 9.co dominance 10. 10. x-linked traits 11. genotypic ratio 12. phenotypic ratio