2. Mendelian Genetics: Dominant & Recessive Review
One allele is DOMINANT over the other (because the dominant allele can “mask” the recessive allele)
genotype: PP
genotype: pp
genotype: Pp
phenotype: purple
phenotype: white
phenotype: purple

3. Review Problem: Dominant & Recessive
In pea plants, purple flowers (P) are dominant over white flowers (p). Show the cross between two heterozygous plants.
GENOTYPES:
PHENOTYPES:
P p
- PP (25%) Pp (50%)
pp (25%)
- ratio 1:2:1 P p
- purple (75%) white (25%)
- ratio 3:1 PP Pp Pp pp

4. Non-Mendelian Genetics
* Incomplete Dominance
*Lethal gene
* Codominance
*complementary genes
* Multiple Alleles
* Sex-Linked Traits

5. a third (new) phenotype appears in the heterozygous condition as a BLEND of the dominant and recessive phenotypes. Ex - Dominant Red (R) + Recessive White (r) = Hybrid Pink (Rr)
Rr = pink
RR = red
rr = white

6. Problem: Incomplete Dominance
Show the cross between a pink and a white flower.
GENOTYPES:
- RR (0%) Rr (50%) rr (50%)
- ratio 1:1
R r r rr Rr
PHENOTYPES: rr Rr
pink (50%)
white (50%)
ratio 1:1

10. The Andalusian fowl is one of the most famous examples of incomplete dominance in animals. A white cock and a black hen will most commonly produce offspring with blue splashes on its feathers, due to the fact that in both parents the inheritance of blue alleles is fifty percent.

11. Incomplete Dominant Cock , white feather , WW Hen, black feather, BB
P WW BB G1
F WB ( Blue feather)
P WB WB G2
F WW WB WB + BB
1: 2 : 1 W B B W B W

12. NN = normal cells NS = some of each SS = sickle cells Codominance
in the heterozygous condition, both alleles are expressed equally with NO blending! Represented by using two DIFFERENT capital letters.
Example: Dominant Black (B) + Dominant White (W) = Speckled Black and White Phenotype (BW)
Sickle Cell Anemia -
NN = normal cells
SS = sickle cells
NS = some of each

13. Sickle Cell Anemia

14. Sickle Cell Anemia Carrier of the disease P NS NS G N S N S
F NN NS NS SS
1:2:1
P SS NS
G S S N S
F NS SS NS SS
1:1
50% infected
50% carrier of the disease

16. Codominance Example: Speckled Chickens
BB = black feathers
WW = white feathers
BW = black & white speckled feathers
Notice –
NO GRAY!
NO BLEND!
Each feather is
either black or white

17. Codominance Example: Roan cattle
cattle can be red (RR – all red hairs) white (WW – all white hairs)
roan (RW – red and white hairs together)

18. Codominance Example:
OX COW
P RR WW G RW
Roan cattle R W

19. Multiple Alleles
there are more than two alleles for a gene. Ex – blood type consists of two dominant and one recessive allele
options. Allele A and B are dominant over Allele O (i)

20. Multiple Alleles: Mouse Fur Colors
Fur colors / black, agouti, yellow

21. Multiple Alleles: Rabbit Fur Colors
Fur colors (determined by 4 alleles): full, chinchilla, himalayan, albino

22. Multiple Alleles
Agouti x chinchilla Agouti Agouti x Himalayan Agouti Agouti x Albino Agouti Chinchilla x Himalayan Chinchilla Chinchilla x Albino Chichilla Himalayan x Albino Himalayan Agouti > Chinchilla >Himalayan > Albino

23. Multiple Alleles: Blood Types (A, B, AB, O)
Rules for Blood Types:
A and B are co-dominant (Both show)
AA or IAIA = type A
BB or IBIB = type B
AB or IAIB = type AB
A and B are dominant over O (Regular dom/rec)
AO or IAi = type A
BO or IBi = type B
OO or ii = type O

26. White color flowers x White color flowers violete color flowers
complementary genes
Definition of complementary gene. :one of two or more genes that when present together produce effects qualitatively distinct from the separate effect of any one of them.
White color flowers x White color flowers
violete color flowers
ttRR TTrr
tR Tr
TtRr TtRr
TR Tr tR tr TR Tr tR tr

27. complementary genes TR Tr tR tr TTRR TTRr TtRR TtRr TTrr Ttrr ttRR

28. Sex-Linked Traits Thomas Morgan , Color of eyes in Drosophilla ,
traits on sex-chromosomesm
Ex: color of eyes in Drosophilla,
red-green blindness in human ( recessive gene on chromosom X

29. Sex-Linked Traits
Gene is attached to the X chromosome only, not found on the Y chromosome at all. (women have XX, men have XY chromosomes). These disorders are more common in boys.
examples: red-green colorblindness
Female xx male yx

30. Trait of blindness in male, Dominant in male , recessive in female.
SEX-INFLUENCED TRAIT
Trait of blindness in male,
Dominant in male , recessive in female.