Chapter 12

1. Chapter 12 Patterns of Heredity and Human Genetics

2. Making a Pedigree • Pedigree: A graphic representation of genetic inheritance • It looks very similar to a family tree • Circle= Female • Square= Male • Carrier: Half-shaded circle or square , a heterozygous individual

4. Analyzing A Pedigree • Read ‘Analyzing a Pedigree’ pg. 310-311 • Disorders are often passed down from generation to generation • Disorders often become scarcer and scarcer with each generation.

5. Review • Review allele ,phenotype, and genotype • At end of 12.1 make a pedigree of family eye color

6. Simple Recessive Heredity • Many disorders are caused by recessive alleles • This includes eye color, hair color, skin tone, and even height.

7. Cystic Fibrosis • A fairly common genetic disorder among white Americans. • Every 1 in 28 white American carries this allele • This is due to a to a defective protein in the plasma membrane and leads to thick mucus in the lungs and digestive track

9. Tay-Sachs Disease • A recessive disorder of the central nervous system • This is common amongst Ashkenazi Jews

10. Phenylkentonuria • This is also called PKU • It results in the absence of enzymes that converts one amino acid to another

11. Simple Dominant Traits • A cleft chin is an example of a simple dominant trait. • You can inherit simple dominant trait from at least one parent.

12. Huntington’s Disease • This is a lethal disorder caused by a rare dominant allele • Huntington’s Disease often results in death

14. 12.2 – When Heredity FollowsDifferent Rules • Complex Patterns of Inheritance – • Simple Mendelian inheritance – controlled by dominant and recessive • Incomplete dominance – third phenotype • Intermediate or incomplete dominance • Ex) Red snapdragon mixed with a white snapdragon = a pink snapdragon

15. Incomplete dominance • Third phenotype • Intermediate or incomplete dominance • Ex) Red snapdragon mixed with a white snapdragon = a pink snapdragon

16. Codominance • Both alleles are expressed • Example in book – Black Chicken with White chicken = a checkered type chicken color.

18. Multiple phenotypes multiple alleles • Pigeons are an example • 3 different alleles of one gene affect feather color • Book pg 317

21. Sex determination • 23 rd pairs of chromosomes differs in males and females. The X and Y • Sex-linked inheritance – traits located on the sex genes. • Boy’s have no “Y” to use as a balance

22. Hemophilia

25. Polygenic inheritance • Skin color and height are this • Each allele is represented by an uppercase letter • Each contributes a small but equal portio of the trait being expressed. • The phenotype is a range.