1. PEDIGREES

2. What is a pedigree?
Pedigree: family history - shows how a trait is passed on through generations
a graphic representation of a family tree
Pedigree can tell you if a trait is passed on genetically and if the alleles are dominant or recessive

3. How do you read a Pedigree?
Generation
Individual
Generation
And
Individual
(III-1)

4. Analyze the Pedigrees
In your group, analyze the 4 pedigrees in your IN
Who’s affected?
Every generation affected?
How many males/females affected?
Are there any carriers?
Is the trait dominant or recessive?

5. What are the four types of pedigrees?

6. AUTOSOMAL DOMINANT
Who will express the trait more often... Males or Females?
They are equally likely to have the trait
Does the trait occur every generation or skip generations?
Occurs every generation
Which genotypes express the trait?
Homozygous Dominant or Heterozygous
***Found in genes on chromosomes
1-22***

7. What’s the genotype for:
AUTOSOMAL DOMINANT
What’s the genotype for:
Individual I-1
Individual I-2
Individual II-7 aa Aa
***Use A or a for alleles*** Aa

8. Autosomal Dominant Disorder Neurofibromatosis

9. They are equally likely to have the trait
AUTOSOMAL RECESSIVE
Who will express the trait more often... Males or Females?
They are equally likely to have the trait
Does the trait occur every generation or skip generations?
Skips generations
Which genotypes express the trait?
Homozygous Recessive
If parents without the trait have children with the trait, what must be the genotype of both parents?
Heterozygous
If a Parent has the trait, their offspring who do not have the trait must have what genotype?
***Found in genes on chromosomes
1-22***

10. What’s the genotype for:
AUTOSOMAL RECESSIVE
What’s the genotype for:
Individual I-2
Individual II-3
Individual III-2 Aa aa
***Use A or a for alleles***
AA or Aa

11. Autosomal Recessive Disorder Albinism

12. Depends on the mother’s genotype
SEX-LINKED DOMINANT
***Found in genes on the X chromosome***
Will all daughters of males with the trait inherit the trait?
YES!...Why?
Can males pass the trait on to their sons?
NO!
Will all daughters and sons of females with the trait inherit the trait?
Depends on the mother’s genotype

13. What’s the genotype for:
SEX-LINKED DOMINANT
What’s the genotype for:
Individual I-1
XHy
Individual II-3
Xhy
Individual II-4
XHXh
***Use XH, Xh, and y for alleles***

14. Sex-Linked Dominant Disorder Rickets

15. Heterozygous (Carriers)
SEX-LINKED RECESSIVE
***Found in genes on the X chromosome***
Is the trait more common in Males than Females? Why?
Males
If a Male has the trait what will be genotype of his daughters?
Heterozygous (Carriers)
What is the chance that a son of a female carrier will inherit the trait?
50%

16. What’s the genotype for:
SEX-LINKED RECESSIVE
What’s the genotype for:
Individual I-2
XhXh
Individual II-2
Xhy
Individual II-3
***Use XH, Xh, and y for alleles***
XHXh
What are the chances that Individual III-5 will have a son with the trait?
100%

17. Sex-Linked Recessive Disorder Color-Blindness
Are you Red-Green Colorblind?

18. Pedigree Activity (Left-Side of your IN)
Paste the pedigree above on the Left-Side of your IN and answer the following questions in your IN.

19. Pedigree Activity
1. What type of pedigree is shown? Autosomal Recessive 2. How many children of individuals II-2 and II-3 have attached earlobes? None 3. How many children of individuals III-3 and III-4 have attached earlobes? Three 4. Is individual I-2 homozygous or heterozygous for free earlobes? Explain. Heterozygous – because the trait was passed on, so the recessive allele had to have been present

20. Pedigree Activity
5. Can you be certain of the genotype of individual II-3? Explain.
No, the recessive allele could
be passed through individual II-2 or III-4
6. Predict the genotype and phenotype of individual V-1.
genotype: homozygous recessive
phenotype: attached earlobes
7. Are any of the descendants of individuals I-1 and I-2 homozygous for free earlobes (FF)? No

21. Create a Pedigree
A man and woman marry. They have five children, 2 girls and 3 boys. The mother is a carrier of hemophilia, an X-linked recessive disorder. She passes the gene on to two of the boys who died in childhood and one of the daughters is also a carrier. Both daughters marry men without hemophilia and have 3 children each (2 boys and a girl). The carrier daughter has one son with hemophilia. One of the non-carrier daughter’s sons marries a woman who is a carrier and they have twin daughters.
Draw this pedigree. Label the genotypes of the individuals above each circle or square. How many people are carriers of hemophilia? How many actually have the disease?