1. Bonus Question 1
Out in the Wild West, you spot a group of wild horses. Some horses in the group have black coats, some have white coats, and some appear to have blue coats. When you get closer, you find that the horses with blue coats actually have tiny patches of white hair and black hair all over their body. What type of inheritance is this? What is the genotype of a black horse? A blue horse?

2. Bonus Question 2
You are a gardener looking to grow your own special flowers for sale. You notice that when you breed red roses with yellow roses, you get an intensely-colored orange rose that is very popular. What type of inheritance is this? In order to maximize your yield of orange roses, what kind of plants (what genotypes/phenotypes) should you cross?

3. Pedigrees: A Family Tree of Traits

4. What is a Pedigree?
Graphic representation of a trait throughout a family’s history
Circle = Female Square = Male
Shaded = Shows trait Unshaded = Does not show trait

5. Additional Symbols Half Shaded = Carrier of Trait
Horizontal Line = Marriage
Vertical Lines = Offspring

6. Make a pedigree in your notes!
Example: Sickle Cell Anemia
A man and woman marry and have three children: a boy and two girls.
The man and his wife are both carriers for sickle cell anemia.
Their son is unaffected. Their older daughter is a carrier for the disorder, and their youngest is born with the disorder

7. Analyze: Dominant or Recessive?

8. Now YOU Try!
Complete the questions for Families 1 and 2 in your packet
You may choose to work individually or with one other person at your table
Analyze Family 3 when finished

9. Sex-Linked Traits Humans have 23 pairs of chromosomes
22 pairs are autosomes
1 pair of sex chromosomes
XX = female
XY = male

10. Sex-Linked Traits
An X-linked trait is determined by an allele on an X chromosome
Color-blindness, hemophilia

11. Sex-Linked Traits
• A male has a single X chromosome, so he will show the effects of any recessive alleles located on his X chromosome.
A female can carry the disease allele without showing it.

12. You Try!
One form of muscular dystrophy is found on a gene on the X chromosome. The disease (m) is found to be recessive to being healthy (M). Cross a heterozygous female with a healthy male.

13. Sex-Linked Traits

14. Genetic Ethics Line-Up

15. You have just met a girl/boy that you like a lot, and you ask them out on a date. During your date, he/she mentions that Huntington’s disease runs in their family, and that their father was recently diagnosed with the disorder. Huntington’s disease is a dominant disorder which leads to decreased muscle coordination and mental decline at a young age (35-44 years). If your date’s father has Huntington’s, you know that there is a 50% chance that he/she will get it eventually. Would you go on a second date with this person?

16. Your father calls for a family meeting to discuss some serious news
Your father calls for a family meeting to discuss some serious news. He just found out that the tremors in his hands and his increasing forgetfulness are the result of Huntington’s disease, which his mother passed away from several years before you were born. Huntington’s disease is a dominant disorder which leads to decreased muscle coordination and mental decline at a young age (35-44 years). If your father has Huntington’s, you know that there is a 50% chance that you might have the gene for it, too. There is currently no cure for Huntington’s. Would you get genetic testing done to find out whether you will get Huntington’s disease?

17. You are the hiring manager at a large company
You are the hiring manager at a large company. You have recently found out that Bob, one of your employees, was diagnosed with Huntington’s disease. Two weeks after you hear about Bob’s diagnosis, Bob’s brother, Jeremy, applies for an open position in the company. You know that Jeremy has a chance of having the dominant gene for Huntington’s, and you can tell from Jeremy’s application that he is 32 years old—close to the age where Huntington’s disease is diagnosed. The job that Jeremy wants involves a long-term commitment to your company, and a lot of mental stress. Would you give Jeremy an interview? Would you give him the job?