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

Incomplete Dominance and Codominance Mendelian Genetics 4/6/2019 Incomplete Dominance and Codominance

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

Mendelian Genetics 4/6/2019 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

Incomplete Dominance r R r All Rr = pink (heterozygous pink) Mendelian Genetics 4/6/2019 Incomplete Dominance r R r All Rr = pink (heterozygous pink) produces the F1 generation Rr

Mendelian Genetics 4/6/2019 Incomplete Dominance

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

Codominance Problem Example: homozygous male Type B (BB) Mendelian Genetics 4/6/2019 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)

Another Codominance Problem Mendelian Genetics 4/6/2019 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)

Sex-linked Traits - Traits (genes) located on the sex chromosomes Mendelian Genetics 4/6/2019 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

Sex-linked Traits Example: Eye color in fruit flies Sex Chromosomes Mendelian Genetics 4/6/2019 Sex-linked Traits Example: Eye color in fruit flies Sex Chromosomes XX chromosome - female Xy chromosome - male fruit fly eye color

Sex-linked Trait Problem Mendelian Genetics Sex-linked Trait Problem 4/6/2019 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

Sex-linked Trait Solution: Mendelian Genetics 4/6/2019 Sex-linked Trait Solution: XR Xr Y XR Xr Xr Y 50% red eyed female (XRXr) 50% white eyed male (XrY)

Mendelian Genetics 4/6/2019 Female Carriers

Mendelian Genetics 4/6/2019 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