1. Multiple Alleles

2. Multiple Alleles Remember: Chromosomes occur in pairs.
(homologous pairs)
the different alleles of a gene occupy the same positions on each chromosome

3. Multiple Alleles
So far each gene we have discussed has been made of two possible alleles.
Ex. B = blue b= yellow
R = red r = white

4. Multiple Alleles
However, it is possible to have several different allele possibilities for one gene.
Multiple alleles is when there are more than two allele possibilities for a gene.

5. The gene for blood type has 3 possible alleles.
Multiple Alleles
In traits with multiple alleles, each individual can carry any two of the several possible alleles.
Ex. BLOOD TYPE
The gene for blood type has 3 possible alleles.
A, B, or O

6. Blood Type In this case both A and B are dominant to O (recessive).
A and B are codominant (both expressed)
So... there are four human blood types
AA, AO A blood type
BB ,BO B blood type
AB AB blood type or
OO O blood type

7. Blood Type

8. Blood Type Practice Problems:
1. A mother is AB and a father is O. Draw the punnett square.
A B O
What is the probability their offspring will have A type blood?
Can they have an offspring with O blood?

9. Blood Type
2. A mother is AO and a father is BB. Draw the punnett square.
What is the probability their offspring will have B type blood?
Can they have an offspring with O blood?

10. Blood Type
3. If a child has AB blood which of the following could NOT be the parents?
a) OO, AB
b) AO, BB
c) BB, AA
d) AO,BO

11. Blood Type