11.1 Basic Patterns of Human Inheritance

1. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Recessive Genetic Disorders • A recessive trait is expressed when the individual is homozygous recessive for the trait.

2. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Cystic Fibrosis • Affects the mucus-producing glands; body can’t get rid of mucus Albinism • Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes

4. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Tay-Sachs Disease • Caused by the absence of the enzymes responsible for breaking down fatty acids • Fat accumulates in the brain, inflating brain nerve cells and causing mental deterioration.

5. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Dominant Genetic Disorders • Huntington’s disease affects the nervous system. • Achondroplasia causes small body size and limbs that are comparatively short.

7. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance

8. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Pedigrees • A diagram that traces the inheritance of a particular trait through several generations

9. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Predicting Disorders • Helps scientists in following inheritance patterns and determining phenotypes and genotypes.

10. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Incomplete Dominance • The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.

11. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Codominance • Both alleles are expressed in the heterozygous condition.

12. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sickle-cell Disease Normal red blood cell • Changes in hemoglobin cause red blood cells to change to a sickle shape. • People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell 7766x

13. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Multiple Alleles • Blood groups in humans • ABO blood groups have three forms of alleles.

14. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Coat Color of Rabbits • Multiple alleles can demonstrate a hierarchy of dominance. • In rabbits, four alleles code for coat color: C, cch, ch,and c.

15. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Coat Color of Rabbits Chinchilla Albino Light gray Dark gray Himalayan

16. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sex Determination • Sex chromosomesdetermine an individual’s gender.

17. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sex-Linked Traits • Genes located on the X chromosome • Red-green color blindness • Hemophilia Sex-Linked Traits

18. Complex Inheritance and Human Heredity Chapter 11 11.3 Chromosomes and Human Heredity Karyotype Studies • Karyotype—graph of homologous chromosomes arranged in decreasing size.