1. Incomplete dominance and codominance are genetic concepts where the phenotype of the offspring is not fully dominated by one allele. An example is pink flowers from white and red parent flowers. 2. Codominance is when the offspring shows traits of both parents, like a checkered chicken from a black and white parent. 3. Multiple alleles exist when more than two alleles control a trait, such as blood types A, B, AB, and O in humans which are determined by proteins on red blood cells.

1. Incomplete Dominance
Codominance
Multiple & Sex Linked Traits

2. Incomplete dominance & Codominance
1. Incomplete dominance
a. genotype is heterozygous(hybrid)
b. phenotype is between the 2 parents
c. dominant
gene can not
fully inhibit
recessive
Example:
white flowers
X red flowers
= pink flowers

3. 2. Codominance
a. offspring shows phenotype of
neither parent
b. both alleles are dominant
Example- black chicken x white
chicken= checkered chicken
=
+

4. B. Multiple and Sex-linked Alleles
1. Multiple alleles: more than 2
alleles control a trait
Example-blood type in humans
a. blood type is determined
by presence or absence of
proteins on the surface of
red blood cells
Examples- A, B, AB, & O

5. Genotype Phenotype-blood type
AA, AO A blood
BB, BO B blood
OO O blood
AB AB blood

6. To determine the blood types of
possible offspring
Parents = A blood, O blood
Genotypes AA, AO OO
A A A O
AO AO O OO
O AO
AO AO OO
AO O
O

7. 2. Sex linked alleles: controlled by
genes located on sex chromosomes
a. usually carried on the X chromosomes
Written as- XH or Xh
b. Females XX, males XY
c. If trait is X-linked, males pass the
trait on to all their daughters, but
none to their sons
d. mothers have 50/50 chance of
passing it to all their children
Examples-colorblindness or hemophilia

8. Quiz
Multiple alleles &
dominance

9. 1. A pink flower is an example of ______.
A. multiple alleles B. codominance
C. incomplete dominance
2. A checkered chicken is an example of ______.
A. codominance B. multiple alleles
C. incomplete dominance
3. Blood type is an example of _____
A. multiple alleles B. codominance
C. incomplete dominance
4. True/false: A blood has the genotypes AA and AO.
5. True/false: fathers can pass sex linked traits like color
blindness on to their sons.

10. 6. In snakes, slithering is dominant over
scooting and having a forked tongue is
dominant over rounded tongues. Predict
the outcome of tongue shape and
movement when 2 individuals with the
following genotypes combine.
SsFf x SsFf