1. Sex-linked traits, Blood Types

2. Sex-linked traits X Y X XX XY X XX XY Male
Sex Chromosomes determined at the moment of : Conception (fertilization)
Female Genotype: XX
Sex chromosome that a female can give: X
Male Genotype: XY
Sex chromosome that a male can give: X or Y
Punnet Square showing the cross of possible chromosomes between a male and female. X Y
Who determines the sex of the child?
Probability of Male: 50% X XX XY
Probability of Female: 50% X XX XY
Male

3. Sex-linked Inheritance
A sex-linked gene is a gene located on the X chromosome. No gene is written on the Y.
Eye color in Drosophilia is sex-linked. The gene for red eyes is dominant over the gene for white
R = Red r=White
Genotype for a homozygous red-eyed female XRXR
Genotype for a heterozygous red-eyed female XRXr
Genotype for a white-eyed female is XrXr
Genotype for a red-eyed male is XRY
Genotype for a white-eyed male is XrY

4. Phen: Red-eyed Female & Red-eyed Male Y XRY XRY
6. If a homozygous red-eyed female Drosophilia mated with a white-eyed male, what are the expected genotypic and phenotypic ratios in the F1 generation? F2?
P: XRXR x XrY
F1: F1
Gen: XRXr & XRY XR XR Xr
XRXr
XRXr
Phen: Red-eyed Female & Red-eyed Male Y
XRY
XRY

5. Gen: XRXR; XRXr; XRY; XrY XR Xr
6. If a homozygous red-eyed female Drosophilia mated with a white-eyed male, what are the expected genotypic and phenotypic ratios in the F1 generation? F2?
F1 Gen: XRXr & XRY
Phen: Red-eyed Female & Red-eyed Male
F2:
F2:
Gen: XRXR; XRXr; XRY; XrY XR Xr XR
XRXR
XRXr
Phen: Red-Eyed Female
Red-Eyed Male; White-eyed Male Y
XRY
XrY

6. Blood Types IB i IB IBIB IBi IBi ii i Gen: IBIB; IBi; ii 2. Father: B
Possible father genotype: IBIB or IBi
1. P: IBi x IBi IB i
Child: AB
Child genotype: IAIB IB
IBIB
IBi
IBi ii i
Mother must carry the A gene
Gen: IAi; IAIA; IAIB
Phen: Type A or Type AB
Gen: IBIB; IBi; ii
Phen: Type B & Type O

7. Phenotypes: Type A & Type B
3.)
List out all the blood types in a punnett square
Work backwards from there. IA i IB
IAIB
IBi
Genotypes: IAi & IBi
IAi i ii
Phenotypes: Type A & Type B

8. i i IA IAi IAi IBi IBi IB Mr. Poe Type O ii Mrs. Poe Type AB IAIB
Mr. Doe Type B IBi or IBIB
Mrs. Doe Type B IBi or IBIB
Mary Type A IAi or IAIA
John Type O ii
Mr & Mrs. Poe Children potential i i IA
IAi
IAi
IBi
IBi IB
Mr & Mrs. Poe can only have have children with type A or B blood. Is John their baby?
Was there a mistake?
YES!!!!!!!!!!!!!