1. Pedigrees Part 1

2. Pedigrees Today, we will be discussing Pedigrees.
What do you think of when you hear the word Pedigree?

3. Create your own family tree
Mom
MS. GLEASON!
Dad
Sister- Stephanie
Nephew- Robert
Brother- Liam
Brother- Patrick
Sister- Kate
Sister- Anne

4. The family tree of genetics
Pedigree Charts
The family tree of genetics
A quick refresher for the teacher on important terms:
Autosomal gene- a gene found on any chromosome except for the sex chromosome. These are chromosomes numbered 1-22.
X-linked gene- a gene found on a chromosome designated as a sex chromosome (X or Y).
Dominant- Refers to an allele that is expressed phenotypically and masks any recessive counterpart.
Recessive- An allele that is not phenotypically expressed when its counterpart is dominant.

5. What is a pedigree? - a genetic family tree
1. A chart of an individual's ancestors used in genetics to analyze inheritance of certain traits, especially of family diseases.

6. Pedigrees are useful for…
2. Pedigrees are useful for tracking the transmission (passing on) of a trait across generations.
3. There are many diseases that are genetic. This means that people can not “catch” the disease, the disease must be inherited from their relatives.

7. Examples of Genetic Diseases
4. These are some of the genetic diseases that you will see used in pedigree questions:
Cystic fibrosis, Sickle Cell Disease, Colorblindness, Hemophilia, Down Syndrome, and Tay-Sachs Disease.

8. KEY
Explains what the symbols on the pedigree mean

9. How to read a pedigree -A circle represents a female
You must learn the symbols of the pedigree charts before you can start to learn how to interpret it. These are the symbols that represent a male and a female.
-A circle represents a female
-A square represents a male

10. Connecting Pedigree Symbols
Married Couple
Siblings (children of
married couple)
These symbols also represent relationships between people. some may have to each other.
-A horizontal line connecting a male and female represents a marriage
-A vertical line and a bracket connect the parents to their children

11. Symbols in a Pedigree Chart
Affected
Carrier
Unaffected
Half shaded means the person isn’t affected but they still carry the trait
These are examples of different types of symbols. These symbols would be the same for males or for females, except for X-linked carrier which is only used for females. So an affected male would be a square that is filled in completely. A deceased female would be a circle with a diagonal slash.
-A circle/square that is shaded means the person HAS the trait/ is AFFECTED.
-A circle/square that is not shaded means the person does not have the trait/ is unaffected.

12. Marriage
Male-DAD
Female-MOM
Has the trait
Female-daughter
Male- Son
Male-Son

13. Organizing the pedigree chart
Generations are identified by Roman numerals (I, II, III) I II
III IV
© 2007 Paul Billiet ODWS

14. Organizing the pedigree chart
Individuals in each generation are identified by numbering from the left to the right
Therefore the affected individuals are II3, IV2 and IV3 I II
III IV
© 2007 Paul Billiet ODWS

15. Practice
How many males in the family are affected with colorblindness?
Which individuals are carriers in generation II?
How many children do the parents of generation I have?
In generation IV, how many females are affected?
How many males are there in generation III?
What is the relationship between individual II-4 and II-5?

16. Practice Problem Answers
How many males in the family are affected with colorblindness? Six
Which individuals are carriers in generation II?
II-2, II-4, II-7
How many children do the parents of generation I have? Five
In generation IV, how many females are affected? One
How many males are there in generation III? Five
What is the relationship between individual II-4 and II-5? They are married.

17. Assignment
Work on the Pedigree Chart Worksheet independently on CODE RED.
Unfinished classwork will become homework