1. Codominance and Pedigree Charts

2. Codominance
Not all traits are either recessive or dominant. In codominance, the alleles are neither recessive or dominant.
Because one is not dominant over the other, both alleles show up!

3. Codominance in Blood Types
There are three alleles that code for blood types:
A (written as IA) - codominant
B (written as IB) - codominant
O (written as i) – recessive

4. Blood Example
A person who inherits an IA allele from one parent and an IB allele from the other parent will have type AB blood

5. Average Blood Types

6. Question 1
A woman with Type O blood and a man who is Type AB are expecting a child. What are the possible blood types of the kid?
___________of kids will be heterozygous with blood Type A
_________________will be heterozygous with blood Type B

7. Question 2
What are the possible blood types of a child who's parents are both heterozygous for "B" blood type?
There is a __________chance that the child will be Type B, and a ________chance that the child will inherit Type O (ii).

8. Traits can be controlled by many genes...
Not all traits are controlled by just two forms of a gene. There can be many genes that control a trait such as skin color!

9. Pedigree Charts
Pedigree charts show how a trait is passed on throughout a family.
They can be used to study the passing on of a genetic disorder.
They are particularly useful when there are large families and are a good family record over several generations.

10. Symbols Square= Male Circle= Female Not shaded= Not infected
Shaded= Has the disorder
Half Shaded= Carrier
Vertical Line= Had children
Horizontal Line= Married

11. Practice

12. Practice Answers Normal Male Affected Male Normal Female
Affected Female
Normal married male and female

13. Generations are identified by Roman numerals

15. Answer questions 1-4 on the bottom of your notes (page 15):
Click the link above for the questions. If they are not answered on your notes, I will take 5 points off!!! Practice makes perfect =)