1. TOPIC: Genetics AIM: What is a Pedigree Chart?

2. TOPIC: Genetics
AIM: How can pedigree charts be used to trace a trait from one generation to the next?
DO NOW: How does Down Syndrome occur?

3. Hypertrichosis is a genetic disorder that triggers uncontrolled hair growth due to physical defects like non-functioning of endocrine gland, infections, mutation, malnutrition, drugs or hereditary factors. Also called werewolf syndrome, it leads to hair formation in unwanted areas generally exempting the hands, feet and eyes. Werewolf syndrome is a rare condition which affects only one person among ten billions. Hypertrichosis either originates during birth or develops after a person grows up especially on the verge of puberty. It is believed to be a genetic disorder that is inherited or occurs as a result of spontaneous mutation.

4. Pedigree
Chart
Visual tool for following a trait through generations of a family

5. Predicts the probability that a baby will be born with a specific trait.

6. Symbols used in pedigree charts
A marriage with five children, two daughters and three sons. The eldest son is affected by the condition.
Eldest child  Youngest child
Normal male
Affected male
Normal female
Affected female
Marriage
© 2007 Paul Billiet ODWS

7. How do you read a pedigree chart?
Not shaded = does NOT have the trait.
Half-shaded = “carrier” (has 1 allele).
Completely shaded = has the trait (homozygous – both alleles for the trait).

8. Generations are identified by Roman numerals.II
III IV

10. How many individuals are represented in this pedigree chart?
A pedigree chart of a family showing 20 individuals

12. Pedigree Charts “Genetic Family Tree”
Now what must the genes be for (1) and (2)??
Both must be “Bb” for them to have a child (5) with “bb” blue eyes.
What about child (3)?
This child must be either BB or Bb, you can’t tell until they have their own children someday.
Click to other remaining genotypes.
Shaded normally indicates a recessive trait, for example all shaded symbols would be “bb” for simple eye color Bb Bb Bb Bb bb Bb
B_?
B_? Bb bb bb
Circles = females
Square = males
Normally shaded symbols indicate a recessive trait.

15. 3. Which child is married? Does the spouse have attached ear lobes?
1. This pedigree shows the inheritance of attached earlobes. Which parent has attached ear lobes?
The father
2. How many children do the parents have? Which child has attached ear lobes?
3 children, Child #1 has attached ear lobes.
3. Which child is married? Does the spouse have attached ear lobes?
Child # 3 is married. Her spouse does not have attached earlobes.
4. Do any of this child’s children have attached ear lobes?
Yes, the son has attached earlobes.

16. What does this pedigree chart show?
How many people are unaffected “carriers”?
How many people are affected by the disorder?
How many carriers are female?

17. What does this pedigree chart show?
How many people are unaffected “carriers”?
How many people are affected by the disorder?
Can we tell if the disorder is dominant or recessive?
How many generations are represented?

18. Royal Hemophilia Pedigree

19. II-1
II-2
Female

20. pure
50%

22. Review 1. Another name for a pure genotype like TT is ______.
3.  Another name for hybrid offspring like Tt is ____.
4.The genetic makeup of an organism is called its ___.
5.The appearance of an organism is also called its ___.

23. 6. R = round r = wrinkled
Give the allele combinations for the following genotypes:
Heterozygous round seeds
Homozygous round seeds
Wrinkled seeds
Give the phenotypes for the following
genotypes:
4. RR
5. Rr
6. Rr

24. 7. An organism having two different alleles for a trait is called
a. heterozygote  
b. homozygous dominant    
c. genotype   
d. monohybrid cross   
8. Mendel hypothesized that each trait is controlled by a factor, now called a
a. gene    b. mate  
c. hybrid    d. dominance    

25. 9. The phenotype of an organism a. represents its genetic composition b. reflects all the traits that are actually expressed c. occurs only in dominant pure organisms d. cannot be seen

26. 10. If an individual possesses two recessive alleles for the same trait, the individual is said to be a. homozygous for the trait            
b. haploid for the trait c. heterozygous for the trait          
d. mutated

27. 11. The human sperm cell contains
44 chromosomes and two X chromosomes
46 chromosomes
44 chromosomes, one X chromosome, and one Y chromosome
23 chromosomes

28. 12. Put the following terms in order from largest to smallest:
Chromosomes
Nucleus
DNA
genes

29. 13. A person who is heterozygous for type A marries a person who is homozygous for type O. What is the chance of them having a child with blood type O?