1. What is a Pedigree… And Nooooo it’s not Dogfood.
Biology I
TCCHS

2. Warm Up /11-12
In typical Mendelian inheritance, a heterozygous individual exhibits the dominant trait. What is the term for when a heterozygote expresses a blend of both the dominant and the recessive trait?
(ex.- blue eyes + green eyes = blue-green eyes)

3. Pedigree—a diagram that shows how a trait is inherited through several generations.

4. Human geneticists illustrate the inheritance of a gene within a family by using a pedigree chart.
Squares = males
Circles = females
Shaded = individual has the trait or condition
Unshaded = individual does not have trait or condition
Horizontal line = marriage
Vertical line = offspring, arranged from left to right in order of birth
Roman numerals - label different generations

5.  = unaffected female = affected female = female carrier
= unaffected male
= male affected by one trait
= male carrier
And more...

6. Patterns of Inheritance
By analyzing patterns of inheritance, biologists can learn about genetic diseases.
If a trait is autosomal, it will appear in both sexes equally and if it is sex-linked, it is usually seen only in males.
The major use of pedigree analysis is in clinical evaluation and counseling of patients with inherited abnormalities.

7. Patterns of Recessive Traits
May appear to “skip” generations
Most children of normal and affected parents are normal
AA x aa ---> Aa
All children of two affected parents will be affected
aa x aa ---> aa

8. Patterns of Recessive Traits
Normal parents may produce affected offspring
Aa x Aa ---> 3/4 normal; 1/4 affected
Affected children often result when parents are blood relatives

9. Patterns of Dominant Traits
Trait tends to appear each generation
Normal and affected individual expected to produce normal and affected children (approximate 1:1 ratio)
Affected individuals generally heterozygous if rare trait
Aa x aa ---> 1/2 Aa; 1/2 aa

10. Patterns of Dominant Traits
At least one parent must be affected in order for children to be affected
Aa x aa
Normal parents will always produce normal offspring
aa x aa ---> aa

11. It is a diagram that shows how a trait is inherited through several generations.
Pedigree for the Albino Trait
Pedigree for a Sex Linked Trait