Sex Determination Xy XX female male Female karyotype Male karyotype X and Y chromosomes Who decides Mom can give X Dad can give X or Y ID: 934626
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Slide1
Sex Determination and Sex-linked Inheritance
Slide2Sex Determination
Xy =
XX=
female
male
Female
karyotype
Male
karyotype
Slide3X and Y chromosomes
Slide4Who decides
?
Mom can give X
Dad can give X or Y
Dads determine sex of babies.
If
dad X
mom X =XX girl
If dad Y mom X =XY boy
X
X
X
Y
X
X
X
X
X
Y
X
Y
Slide5Nondisjunction
XO- Turner Syndrome
XXX-
Trisomy X
XXY- klinefelter SyndromeXYY- Jacob SyndromeVery often, symptoms are slight due to X-inactivation and the small amount of genes found on the Y chromosome
Slide6SEX CHROMOSOMES CONTAIN
GENES
THAT CODE FOR TRAITS =
SEX LINKED TRAITS
Slide7Drosophila melanogaster
Model organisms
Easily contained
Short generation time (10 day)
High fecundity (has many offspring at a time ~100 eggs laid per day)Eye color is a sex-linked trait
Slide8Both Males and Females Inherit X Chromosomes: Males XY; Females XX
X-LINKED GENES
:
Genes carried on the X chromosome
EX: _____________
_____________
_________________________
Hemophilia
Colorblindness
Muscular Dystrophy
Slide9Make a cross with an X-linked gene
Hemophilia is an
___________ _________
disease
X-linked
recessive
Use
___ for normal dominant blood
clotting gene.
Use ___ for recessive hemophilia gene.
On X chromosome write it as _____
H
h
X
h
Slide10Mother
Without hemophilia = X
X
Without hemophilia = X
X With hemophilia = X
X
Father
Without hemophilia = X y
With hemophilia = X y
H
H
H
h
h
h
CARRIER
H
h
Key!
Slide11X
H
y
X
H
X
h
Make a cross with an X-linked gene
Carrier Mom
Normal Dad
X
H
X
H
X
H
y
X
H
X
h
X
h
y
GIRLS
_______ = normal
_______ = look normal
but are
CARRIERS
BOYS
_______ = normal
_______ = hemophilia
1/2
1/2
1/2
1/2
Slide12Y linked genes ________ show up in males.
X linked recessive genes appear __________ in males than females.
Females can be __________ for X linked
recessive traits.
Males can _________ carriers for X linked
recessive genes. They either have trait OR are normal.
ONLY
more often
CARRIERS
NEVER BE