Incomplete Dominance

1
Incomplete Dominance Codominance
2
Incomplete Dominance- Blending!

• In Incomplete Dominance, every genotype has its
  own phenotype. (2 alleles produce 3 phenotypes.)

3
Incomplete Dominance

• Blending- One allele not completely dominant over
  the other.
•  
• Result Heterozygous phenotype somewhere in
  between homozygous phenotype.

4
1. Incomplete Dominance

• Examples
• Trait Flower Color
• Expressions Red x White ? Pink
• RR Red RW pink WW white
• straight hair, wavy, curly

5
Incomplete Dominance Use 2 different capital
letters
6
Codominance

• In codominance, neither allele are dominant both
  are expressed.  
• Black chicken
• X white chicken
• ____________
• Black and white chicken

7
2. Codominance

• Both alleles contribute to the phenotype.
• Example In come chickens
• Black Chicken x White ? Speckled Chicken

8
YOU tell me which type of dominance
Codominance!
9
Type of Dominance?
10
Type of Dominance?
Incomplete Dominance!
11
Multiple Alleles

• There are more than two alleles for a trait
• Blood type in humans
• Blood Types?
• Type A, Type B, Type AB, Type O
• Blood Alleles?
• A, B, O (in book IA, IB, I)

12
Rules for Blood Type

• A and B are codominant
• AA Type A
• BB Type B
• AB Type AB
• A and B are dominant over O
• AO type A
• BO type B
• OO type O

13
Problem Multiple Alleles

• Show the cross between a mother who has type O
  blood and a father who has type AB blood.

O O
GENOTYPES
- AO (2) BO (2) - ratio 11
A B
PHENOTYPES
- type A (2) type B (2) - ratio 11
14
Problem Multiple Alleles

• Show the cross between a mother who is
  heterozygous for type B blood and a father who is
  heterozygous for type A blood.

GENOTYPES
A O

• AB (1) BO (1)
• AO (1) OO (1)
• - ratio 1111

B O
PHENOTYPES

• type AB (1) type B (1)
• type A (1) type O (1)
• - ratio 1111