1. Notes: Types of Inheritance

3. Test Cross
Used to determine the genotype of an individual that displays a dominant trait.
Don’t know whether the genotype is PP or Pp

4. Test Cross
Used to determine the genotype of an individual that displays a dominant trait.
Either PP or Pp
Cross with homozygous recessive (pp)
If in the offspring, there are pp, then the parent had to be Pp

5. Types of Inheritance Complete Dominance Incomplete Dominance
Codominance
Sex-linked
Polygenic
Epistasis
You will be responsible to complete punnett squares for the types in red

6. Complete Dominance One allele is completely dominant over the other
Only two phenotypes exist
One phenotype is masked
The heterozygous phenotype shows dominant trait
Ex: Purple flowers are dominant to white
PP= purple
Pp= purple
pp= white

7. Complete Dominance Autosomal Genetic Disorders.
Carrier: A heterozygote for a recessive disorder
(ex/ Cc).
Carrier does not show symptoms but can pass recessive allele to offspring
Affected person must inherit two recessive alleles
Example Cystic Fibrosis, Tay-sachs, sickle-cell anemia
CC &Cc = unaffected
cc = affected

8. Practice Problem
A male and female are both carriers for sickle-cell anemia. What percent chance do they have of having a child with sickle-cell anemia?

9. Incomplete Dominance
Neither allele is completely dominant over the other

10. Incomplete Dominance
Neither allele is completely dominant over the other
Three phenotypes exist
The heterozygous phenotype shows blended trait

11. Incomplete Dominance
Neither allele is completely dominant over the other
Three phenotypes exist
The heterozygous phenotype shows blended trait
Ex: Flowers can be pink, red, or white.
RR=red
rr= white
Rr =pink

12. Incomplete Dominance Cross two pink flowers
What percent of their offspring will have white flowers?

13. Fish can be green (GG), blue (BB), or teal (GB)
Green (GG) Teal (Gg) Blue (gg)

14. Codominance
Both alleles are dominant

15. Codominance Both alleles are dominant Three phenotypes exist
Neither phenotype is masked
The heterozygous phenotype shows both traits at once

16. Codominance = X Both alleles are dominant Three phenotypes exist
Neither phenotype is masked
The heterozygous phenotype shows both traits at once. X =
red (RR) white (WW)

17. Codominance = X Both alleles are dominant Three phenotypes exist
Neither phenotype is masked
The heterozygous phenotype shows both traits at once. X =
red (RR) white (WW) red & white(WR)

18. Codominance
EX: In Smileys, eye shape can be starred, circular, or a circle with a star.
Write ALL the phenotypes and genotypes that exist.

19. Codominance
EX: In Smileys, eye shape can be starred, circular, or a circle with a star.
Write ALL the phenotypes and genotypes that exist.
CC = circle SS = star SC = circle-star

20. Codominance Example: Blood Types
Trait controlled by three alleles, with two that are codominant and one recessive
IA : produces A antigens on surface of cell
IB : produces B antigens
i: does not produce antigens

22. Genotypes
Phenotypes
AA or AO
Type A
BB or BO
Type B AB
Type AB OO
Type O

23. Practice Problem
What possible blood types could the children of a homozygous A female and a male with AB blood have?
Parents Genotype
_______X ________

25. Sex Linked Disorder/trait found on the “X” chromosome
Which gender has more instances of having an x-linked disorder?

26. Sex Linked Disorder/trait found on the “X” chromosome
Which gender has more instances of having an x-linked disorder?
Men-Males have no second copies of X-linked genes (XY).
Females have two X chromosomes (XX) so if one has a defect they can use the other normal X chromosome.

27. Sex-Linked EX: color blindness Punnett square determines sex and trait
First, Use X and Y to show gender
Second, use a letter on the X chromosome to show which allele they inherited.

28. Sex-Linked EX: color blindness Punnett square determines sex and trait
First, Use X and Y to show gender
Second, as a letter on the X chromosome to show which allele they inherited.
Possible genotypes and phenotypes:
XR XR = Female, normal vision
XR Xr = Female, normal vision
Xr Xr = Female, color blind
XR Y = Male, normal vision
Xr Y = Male, color blind

29. Sex Linked
What percentage of offspring would be color blind if a female carrier and a male who has normal vision had children?

30. Sex Linked
What percentage of offspring would be color blind if a female carrier and a male who has normal vision had children? Step 1: Determine genotype of parents ____________ x ____________

31. Sex Linked
Step 2: set up and complete punnett square. What percent of their children would be colorblind?

35. Polygenic Many genes may interact to produce one trait
Ex: Skin color result of four genes that interact to produce range of colors

36. Epistasis One gene controls many traits EX: Albinism
Albinos are unable to synthesize melanin, the pigment molecule responsible for most human coloring