Chromosomal Basis of Inheritance

1. Chromosomal Basis of Inheritance Tracing Heredity through Inheritanceof Specific Chromosomes

2. Sex Determination Sex Chromosomes: homologous chromosomes that differ in size and genetic composition between males and females

3. Sex Determination Autosome: any chromosome that is not a sex chromosome Humans have 22 pairs of autosomesand 1 pair of sex chromosomes

4. Human Karyotype showing homologous chromosome pairs

5. Sex Determination Female Male XX x XY ½ X ½ X ¼ XX ¼ XX ½ X ½ Y ¼ XY ¼ XY Phenotypic Ratio of Offspring ½ Female + ½ Male

6. X-linked Genes Hemophilic Male Non-hemophilic Female (father is hemophilic) XhY x XHXh ½ XH ½ Xh ¼ XHXh ¼ XhXh ½ Xh ½ Y ¼ XHY ¼ XhY Phenotypic Ratio of Offspring ¼ hemophilic males + ¼ non-hemophilic males ¼ hemophilic females + ¼ non-hemophilic females

7. Terms Specific toSex-linked Genes

8. Patterns of Inheritance • Autosomal Dominant • Autosomal Recessive • X-linked Dominant • X-linked Recessive • Y-Linked Inheritance

9. Pedigree for Huntington’s Disease, an Autosomal Dominant Trait

10. Pedigree for Albinism, an Autosomal Recessive Trait

12. Pedigree for Colorblindness, an X-linked Recessive Trait