1. Chapter 12 – Patterns of Heredity and Human Genetics
Objectives
Identify information presented on a karyotype
Recognize the difference between male and female karyotypes
Distinguish between normal and abnormal karyotypes

2. Take out a sheet of paper and write your name along with your lab partners.
1. Look Figure on page 329. Explain what you think the picture is showing? 2. What do you think the numbers as well as letters on the photograph represent?

3. Karyotype pg. 329 Chromosomes come in pairs, inherited from parents
Half from mom & half from dad
Humans have 23 pairs of chromosomes, 46 total.
Any more or less = abnormality
Sex Chromosomes – Called X and Y
Autosomes – all non-sex chromosomes

4. Karyotype Fig pg. 329
Picture of cell taken during the process of metaphase
3. Why metaphase?
4. Looking at the Figure 12.20, how are the chromosomes arranged?
5. Do you think male and female karyotypes are the same? Explain.
Chromosomes arranged by length, banding pattern, centromere location
Comparison against a normal karyotype

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

8. 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

9. Textbook pg. 310 Fig. 12.2 7. How many generations are shown?
8. How many offspring did I-1 and I-2 have?
9. How many boys did III-3 and III-4 have?
10. How many girls did II-1 and II-2 have?
11. What kind of trait (dominant or recessive) is being passed down?
12. What genotypes must I-1 and I-2 be in order to have a child with this trait?
13. What is the probability that they would have this type of child? Show a Punnett square

10. 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

11. 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 or homozygous dominant

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

13. 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

15. 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

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

17. 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

18. 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

19. 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?

20. Blood Types
BLOOD TYPE.ppt

21. 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

23. Red-Green colorblindness
Hemophilia (blood doesn’t clot properly)
Male Pattern Baldness
Duchenne Muscular Distrophy (muscular degeneration leading to eventual paralysis)

24. 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

25. 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?

26. Polygenic Inheritance
Characteristics that are influenced by several genes