Download We Are Family! Introduction to Pedigree Genetics

We Are Family! Day 2
Introduction to Pedigree Genetics
Week 12
Rincon High School
Go Rangers!
Objectives
 The Student will be able to:
 1.) Finish the 2 trait Punnet square practice problems.
 2.) Sketch and describe the basic anatomy of a family
pedigree.
 3.) Use the information from a pedigree to infer genotypes
and answer application questions.
Different Modes of Inheritance:
3.) X-Linked Recessive
 The sex of an individual has been linked to certain disorders,
we’ll finish by examining these pedigrees.
 New Nomenclature
XA = normal Xa = the trait (a genetic disease or abnormality) Y
= Y chromosome (males only)
 Examples for a Female: XAXa, XAXA, XaXa
What would the male sex genotype look like?
 Examples for Males: XAY, XaY 
New Term: Males are consider “Hemizygous,” for their sex
chromosomes. Hemi meaning half.
Let’s Practice
Assign the genotypes
(Use X and Y’s now).
Is it possible that the pedigree
above is for an X-linked
recessive trait?
Keep Going, almost there!
Assign the genotypes
(Use X and Y’s now).
Is it possible that these
pedigrees represent an X-linked
recessive trait?
Different Modes of Inheritance:
3.) X-Linked Dominant
 XA =the trait (a genetic disease or abnormality) Xa =
Normal Y = Y chromosome (males only)
 Common X-Linked Dominant Diseases: Few and Rare!
 Vitamin D resistant rickets
 Rett's syndrome
 Fragile X syndrome
Getting the hang of this yet? Let’s see!
Our First Genetic Case Study!
 When Queen Victoria of England was seventeen, she met one
of her many cousins, Prince Albert of Saxe-Coburg. She fell
deeply in love with him, and several years later, when they
were both twenty years old, Victoria proposed to Albert.
 They were married on February 11, 1840; both were
deliriously happy, and Victoria made Albert Prince Consort,
giving him an equal say in the running of the country. What
neither of them knew at the time was that Victoria was
carrying the gene for hemophilia.
Your Mission!
 You are a genetic detective tasked with figuring out what type of
inheritance pattern this disease is following in Queen Victoria’s
family pedigree.
 You’ve conducted your preliminary research and constructed a
rough pedigree of the family history. You’ve also concluded that
the disease is not autosomal.
 Help us Obi Wan Kenobi you’re our only hope!....I know Ms. G, 5
bucks.
Don’t forget Homework due tomorrow!
1.) Family Pedigree’s Due
2.) Punnett Square challenge problem
due (Optional)