1. Other Types of Inheritance
Unit 6C
Other Types of Inheritance

2. Yesterday we talked about Dominant and Recessive Traits.
Which human trait did I say was not controlled by Dominant/Recessive genes?
Skin Color
What happens when an African American crosses with a Caucasian?
The child is a blend of the colors.
It is Intermediate between Dark and Light Skin.

4. Traits that are controlled by pure dominance or recessiveness are controlled by “Complete Dominance”.
Traits that are not controlled by Complete Dominance can be controlled by:
Incomplete Dominance
Codominance
Multiple Alleles and Genes

5. Incomplete Dominance
In Incomplete Dominance, neither trait is completely dominant, so there is a blending of traits.
When representing Incomplete Dominance, two different capital letters are used. RR RW WW

6. Incomplete Dominance Example
Flower color is controlled by incomplete dominance.
Use a Punnett Square to cross a Red flower with a Yellow flower.
Genotype:
100% RY
Phenotype:
100% Orange R R Y R Y R Y Y R Y R Y

7. Codominance Traits can also be controlled by Codominance.
In Codominance, both traits are dominant, so both traits show up.
In Codominance, two different capital letters are used. WW WB BB

8. Codominance Example
Flower color can also be controlled by codominance.
Use a Punnett Square to cross a Red flower with a Yellow flower.
Genotype:
100% RY
Phenotype:
100% Striped R R Y R Y R Y Y R Y R Y

9. STOP teaching

10. Codominance Example
Codominance is what controls the human ABO blood type.
Your red blood cells carry antigens (a protein) on their surface.

11. Your blood also contains antibodies against antigens on blood cells that do not belong in your body.

12. What happens if you give type A blood to someone who has type B blood in their body?
The blood coagulates…it clumps up.
Then what?
The person dies.

13. Let’s do a Punnett Square with Blood Types.
Genotype:
50% AA
50% AB
Phenotype:
50% Type A
50% Type AB
Let’s do a Punnett Square with Blood Types.
My Mom is type AB and my Dad is type AA.
What could I be? A B A A A A B A A A A B

14. Genotype:
50% AO
50% OO
Phenotype:
50% Type A
50% Type O
My Mom has type O blood and my dad has type AO blood. What type could I have? O O A A O A O O O O O O

15. Multiple Alleles & Polygenic Traits
The human genotype is VERY complicated. Many of our traits are carried out by more than one set of genes.
Each set of genes can also have multiple alleles
These different genes can also be on different chromosomes.
Yellow/Green/Brown
Black/Brown
Gray/Blue
Purple/Green
All 4 sets of genes to the left code for eye color!! #4
#12
#13

17. BECAUSE YOU ASKED: Heterochromia can be acquired several different ways:
From parents as a Dominant Trait
As a mutation (called mosaicism) during development of the embryo
As a result of eye trauma or disease.

18. The ABO blood type is actually controlled by multiple alleles as well.
ABO blood type is controlled by these 3 alleles: IA IB i
We wrote the ABO genes as AA or AB, but they are actually written like this:
IAIA = A
IAi = A
IAIB = AB
IBIB = B
IBi = B
ii = O

19. So, let’s do the same Punnett Square that we did earlier, except let’s use the proper letters this time.
Genotype:
50% IAi
My Mom has type O blood and my dad has type AO blood. What type could I have?
50% ii
Phenotype:
50% Type A
50% Type O i i IA IA i IA i i i i i i

20. So far, all the inheritance that we have discussed has been inheritance on the autosomes.
Tomorrow, we will talk about inheritance of traits that are on the sex chromosomes.