1. 28N
Multiple Alleles

2. Multiple Alleles = more than 2 alleles are present for one gene
Example: Human ABO blood types-there are 3 alleles
Genotypes: Blood Types:
IAIA or IAi AA or AO Type A
IBIB or IBi BB or BO Type B
IAIB AB Type AB
ii OO Type O

3. AB (Universal Recipient)
Multiple Alleles
Blood Group
Can give blood to
Can receive blood from
AB (Universal Recipient) AB
AB, A, B, O A
A, AB
A, O B
B, AB
B, O
O (Universal Donor) O

4. Percentage of the Population
Multiple Alleles
Blood Type
Percentage of the Population O
43% A
40% B
12% AB 5%

5. Multiple Alleles Example 1: homozygous type A female X
heterozygous type B male
Genotype Ratio:
50% IAIB
50% IAi
Phenotype Ratio:
50% Type AB
50% Type A IA IA IB
IAIB
IAIB i
IAi
IAi

6. Multiple Alleles Example 2: Type O female X Type AB male
Genotype Ratio:
50% AO
50% BO
Phenotype Ratio:
50% Type A
50% Type B O O A AO AO B BO BO

7. Charles Drew Found that blood cells can be frozen and stored
Set up blood banks for transfusions

8. Polygenic Traits = traits controlled by two or more genes
Examples: Skin, eye color, height
influenced by the combination of different genes
AABBCC = most amount of melanin (pigment) – darkest skin
aabbcc = least amount of
melanin –lightest skin
AaBbCc = medium colored skin

9. Environmental Influence = an individual’s phenotype may depend on conditions in the environment
Examples:
Arctic fox – white in the winter and brown in the summer because the pigment producing genes do not work in the cold

10. Environmental Influence
Siamese cats and Himalayan rabbits – have dark colored fur on their extremities
The allele that controls pigment production can only function at the lower temperatures of those extremities