1. Patterns of Heredity and Human Genetics
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 Follows Different 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.