1. HUMAN GENETICS
Chapter 12, Section 1

2. Pedigree
Pedigree = map of inheritance of genetic traits from generation to generation

3. Symbols on a Pedigree Circle = Female Square = Male
Shaded = Affected Unshaded = Unaffected
Adjoining line = Married/Mating
Connected by an adjoining line = Offspring
Roman Numeral = Generation

4. Recessive Heredity Caused by recessive alleles
Attached earlobes, Cystic fibrosis (defective protein leads to excessive mucus production in lungs), Albinism
Individual will only display the recessive phenotype if its genotype is homozygous recessive (aa)

5. Dominant Heredity Caused by dominant allele
Freckles, Widow’s peak, Hitchhickers thumb, Huntington’s disease (brain degeneration, doesn’t appear until later in age), immunity to poison ivy
Individual will display the dominant phenotype if its genotype is heterozygous(Aa) or homozygous dominant(AA)

6. Textbook pg. 310 Fig. 12.2
With your lab partner answer the following questions on a separate sheet of paper.
How many generations are shown?
How many offspring did I-1 and I-2 have?
How many boys did III-3 and III-4 have?
How many girls did II-1 and II-2 have?
What kind of trait (dominant or recessive) is being passed down?
What genotypes must I-1 and I-2 be in order to have a child with this trait?
What is the probability that they would have this type of child? Show a Punnett square

7. When Heredity Follows Different Rules
Chapter 12, Section 2

8. Incomplete Dominance
Incomplete Dominance = phenotype of a heterozygote is in between the dominant & recessive phenotypes, appearance of a third phenotype.
No Longer Upper and Lowercase letters A or a
Flowers known as Snapdragons come in 3 colors but have 2 alleles, R and R’
R’R’ = White
R’R or RR’ = Pink
RR = Red

10. Sample Problems
Cross the following snapdragons and give the genotype and phenotype ratios. Red x White – Phenotypic Ratio White : Pink : Red Genotypic Ratio R’R’: R’R : RR Pink x Pink – Phenotypic Ratio

11. Text pg. 316 Figure 12.7 Red x White = all pink
Pink x Pink = 1Red: 2Pink: 1White

12. Genetics Review
Mendelian Genetics – Simple Dominant & Recessive Traits (Tall TT or Tt or short tt)
Incomplete Dominance – 3 phenotypes (FF = red, FF’ = pink, F’F’ = white)
Pedigree – Map to show how traits are passed from parent to offspring (not shaded – doesn’t have trait, half shaded – carrier, shaded – has trait

13. Codominance
Both alleles for a gene are expressed in a heterozygous individual
Black Feathers FBFB = Black Feathers
White Feathers FW FW = White
When the 2 alleles are combined a chicken with both black and white feathers is created.
Erminette chickens FBFW = Black & White
Neither allele is dominant or recessive

14. Codominance Practice Problems
Cross a chicken that is homozygous for the black alleles with a chicken that is homozygous for the white alleles.
What color feathers did the offspring have?
Cross 2 chickens from the F1 generation to make the F2 generation?

15. Blood Types
BLOOD TYPE.ppt

16. Genetic Testing
Genetic Tests are now available that can tell you the probability that an individual will have a certain disorder. Write Yes or No on the whiteboard to answer the following questions.
Would you want to be tested?
Would you have a significant other tested?
Would you have your child tested?
Would you agree to be tested if you are an employee?
Would you as an employer require job applicants to take a test?

17. Sex Determination & Sex-linked Inheritance
Combination of sex chromosomes (X and Y) determine an individual’s gender
Males XY, X chromosome comes from mom & Y chromosome comes from dad
Females XX, both mom & dad give an X chromosome
Sex-linked Traits = traits controlled by genes on sex chromosomes

19. Examples of X Linked Traits
Red-Green colorblindness
Hemophilia (blood doesn’t clot properly)
Duchenne Muscular Distrophy (muscular degeneration leading to eventual paralysis)

20. Most of sex-linked traits are found on genes on the X chromosome (X-linked trait) because it is larger than the Y chromosome
X-linked traits display more in males because they only have 1 X chromosome, whereas females get 2 X chromosomes so they can be carriers of the trait but not display the phenotype

21. Color Blindness - Recessive Trait B = Normal b = color blind
Males
XBY = Normal XbY = Color Blind
Females
XBXB = Normal
XBXb = Carrier (Normal)
XbXb = Color Blind
Can males be carriers for color blindness? Why or why not?

22. Sex Linked Crosses Cross a color blind male with a carrier female?
What is the probability you will get a color blind child?
What is the probability you will get a color blind male? Only look at males.
What is the probability you will get a carrier female? Only look at the females

23. Polygenic Inheritance
Characteristics that are influenced by several genes