1. Non-Mendelian Genetics
Aim: What are some other ways traits are shown?

2. Incomplete Dominance
A. Both alleles contribute to the phenotype of a heterozygous individual to produce a blending (mixture) of either dominant gene.
Example: cross between a red flower & a white flower = pink flower.

3. Incomplete Dominance
B. In incomplete dominance, use capital letter for both traits since they both influence outcome. R W RW
Offspring are 100% pink

4. Incomplete Dominance C. Crossing a hybrid 25% Red 50% Pink 25% White RRR RW WW
25% Red
50% Pink
25% White

5. Co-Dominance A. Two dominant alleles are expressed at the same time.
1. Results in simultaneous expression of both alleles in the phenotype of a heterozygous individual.
Example: Roan cattle w/mixture of red & white hairs; human blood type.

7. Co-Dominance
B. Co-dominance is written with capital letters & superscripts.
CR= Red
CW= White
CRCW= Roan CR CW
CRCW

8. Multiple Alleles
A. There may be more than 2 alleles for a trait in a species.
1. Individuals cannot have more than 2 alleles for each trait.
Example: Blood type A, B, AB, O

9. Sex Determination
A. Sex is genetically determined at fertilization when a sperm cell containing an X or Y chromosome unites w/ an egg cell containing an X chromosome.
1. XX: produces female
2. XY: produces male

10. Sex-Linked Traits
A. Genes for certain traits are located on the X chromosome.
1. These genes do not have a corresponding allele on the Y chromosome.
2. Many of these genes are recessive therefore they are expressed more in males than females.
Example: Hemophilia; colorblindness
3. Females are often carriers.

11. The Inheritance of Hemophilia

12. Sex-Linked Traits
4. Pedigree charts are used to show the presence or absence of particular inherited traits in humans.