1. Non- mendelian Genetics Incomplete Dominance Codominace Multiple alleles (blood types) Sex-linked Traits

2. Incomplete Dominance and Codominance
Mendelian Genetics
2/24/2019
Incomplete Dominance and Codominance

3. Incomplete dominance is when the dominant trait is not completely dominant over the reccessive trait Heterozygote produces a mix between the two parental types Snapdragon example: RR = Red RW = Pink WW = White

4. Mendelian Genetics
2/24/2019
Incomplete Dominance
F1 hybrids have an appearance somewhat in between the phenotypes of the two parental varieties.
Example: snapdragons (flower)
red (RR) x white (rr)
RR = red flower
rr = white flower R r

5. Incomplete Dominance r R r All Rr = pink (heterozygous pink)
Mendelian Genetics
2/24/2019
Incomplete Dominance r R r
All Rr = pink
(heterozygous pink)
produces the
F1 generation Rr

6. Mendelian Genetics
2/24/2019
Incomplete Dominance

7. 3. type AB = AB (both A and B dominate) 4. type O = OO
Codominance occurs if two alleles are dominant and thus both forms of the trait are expressed at the same time.
- Also knowns as multiple alleles
Example: blood type
1. type A = AA or AO
2. type B = BB or BO
3. type AB = AB (both A and B dominate)
4. type O = OO

8. Codominance Problem Example: homozygous male Type B (BB)
Mendelian Genetics
2/24/2019
Codominance Problem
Example: homozygous male Type B (BB)
x heterozygous female Type A (AO) B A O AB BO
2:4 or 50% = AB (type AB)
2:4 or 50% = BO (type B)

9. Another Codominance Problem
Mendelian Genetics
2/24/2019
Another Codominance Problem
Example: male Type O (OO) x female type AB (AB) O A B AO BO
2:4 or 50% = AO (type A)
2:4 or 50% = BO (type B)

10. Sex-linked Traits - Traits (genes) located on the sex chromosomes
Mendelian Genetics
2/24/2019
Sex-linked Traits
- Traits (genes) located on the sex chromosomes
- Sex chromosomes are X and Y
- XX genotype for females
- XY genotype for males
- Many sex-linked traits are carried on X chromosome only

11. Sex-linked Traits Example: Eye color in fruit flies Sex Chromosomes
Mendelian Genetics
2/24/2019
Sex-linked Traits
Example: Eye color in fruit flies
Sex Chromosomes
XX chromosome - female
Xy chromosome - male
fruit fly
eye color

12. Sex-linked Trait Problem
Mendelian Genetics
Sex-linked Trait Problem
2/24/2019
Example: Eye color in fruit flies
(red-eyed male) x (white-eyed female) XRY x XrXr
Remember: the Y chromosome in males does not carry traits.
RR = red eyed
Rr = red eyed
rr = white eyed
XY = male
XX = female XR Xr Y

13. Sex-linked Trait Solution:
Mendelian Genetics
2/24/2019
Sex-linked Trait Solution: XR Xr Y
XR Xr
Xr Y
50% red eyed female (XRXr)
50% white eyed male (XrY)

14. Mendelian Genetics
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Female Carriers

15. Mendelian Genetics
2/24/2019
Female Carriers
Males only have one X chromosome while females have two X chromosomes This means females have less of a chance of expressing the sex-linked trait, they are usually carriers of sex-linked traits Males are more likely to express the sex-linked trait