1. Making a Pedigree Chart
A family history of a genetic condition

2. Quick Review Genotype = what genes someone has
Genes are usually represented by a letter, a capital letter for the dominant trait, a small case for the recessive.
Example: Tongue Rolling is dominant, so we use R to represent the tongue rolling
Inablility to roll your tongue is recessive so we use r to represent the non-rolling gene
For every trait, you get a gene from each parent

3. Genotypes and Phenotypes
Mom and Dad are Rr-that is their genotype, they can also be described as heterozygous-they have 1 of each gene
What is their PHENOTYPE?
The youngest son has a genotype of rr-he is Homozygous recessive-2 copies of the recessive gene
His phenotype?
tongue rollers Rr Rr
I can’t
Roll my
Tongue!
non-roller Rr rr Rr Rr

4. Some common dominant and recessive traits
Widow’s peak is dominant.
You can be homozygous dominant (WW) or heterozygous (Ww) and you will have widow’s peak
What is your genotype and phenotype if you’re homozygous recessive?
ww, no widow's peak

5. Making a Pedigree Chart
Pedigree charts are made to chart family history and see how traits are passed
A genetic counsellor will use pedigree charts to help determine the distribution of a disease in an affected family

6. Symbols Shade individuals that have the trait you’re studying
Boys = squares (Lucy always calls Charlie Brown a ‘block head’)
Girls = circles

7. Married-connected at side
Siblings-connected at TOP not at the side (hopefully not siblings AND married)
Oldest child-to the left
Question-if shaded individuals in this pedigree have blue eyes, what is the GENOTYPE of the parents?
both must be Bb

8. Other
Divorced, separated
Deceased
Identical twins
Fraternal twins

9. Organizing the pedigree chart
Generations are identified by Roman numerals I II
III IV

10. Organizing the pedigree chart
Individuals in each generation are identified by Arabic numerals numbered from the left
Therefore the affected individuals are II3, IV2 and IV3 I II
III IV 3 4 5 6 7 2 1

11. What’s going on? Shaded = blue eyes
1 and 2 split after having 4, 2 then had kids with 3 and split with her too after 5-9 were born
Genotypes of 1, 4,7?
Genotypes of 2 & 3?
Genotypes of 5,6, 8, 9, 10, 11, 12? 1 2 3 bb 6 10 4 5 7 8 9 Bb 12
could be BB or Bb 11
In what generation are there twins?
III

12. Time to practice…
Complete the practice worksheet on pedigrees in class (we will review)
Pedigree swap activity
Homework assignment – YOUR CHOICE!

13. Make your own pedigree
Using your own family, make your own pedigree chart
Must at LEAST include grandparents, parents, & your generation
Pick one easy dominant or recessive trait and shade individuals that have it. You can guess who has it if you don’t know for sure. (Don’t pick a trait that EVERYONE in your family has)
Label yourself, grandparents, cousins, etc
Put a key on the pedigree so I know what shaded means. Ex.- shaded people have widow’s peak
OR…you may create a pedigree chart for a fictional family of your choice. For example, a family in a book you read or a movie you have seen (ex: Twilight series, Harry Potter, etc)