SEX-LINKED and SEX INFLUENCED TRAITS

1
SEX-LINKED and SEX
INFLUENCEDTRAITS
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SEX DETERMINATION

• XX

female
male
Xy
3
Who decides?
X
X

• Mom can give X
• Dad can give X or y

X X
X X
X
X y
X y
y
Dads determine sex of babies. If dad gives X
with moms X girl If dad give y with moms X
boy
4
SEX CHROMOSOMES CAN CARRY OTHER GENES TOO
___________________
SEX LINKED TRAITS
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Sex-Linked Traitstraits that are directly
linked to a sex chromosome
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SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
7
Sex chromosomes can carry other genes

• Y-LINKED GENES
• Genes carried on Y chromosome

EXHairy pinna
Y linked
males.
_________genes only show up in _______
8
Make a cross with a y-linked gene
Hairy ears is a ________________
________________ trait
Y linked
dominant
H
Use ______ for hairy ears. Use ______ for
recessive normal ears. On y chromosome so write
it as ________
h
yH
9
Make a cross with a y-linked gene
X
X
ALL GIRLS ____________
X X
X X
X
Normal ears
ALL BOYS ____________
Hairy ears
X yH
yH
X yH
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Sex chromosomes can carry other genes

• X-LINKED GENES Genes carried on the X chromosome

EX _____________ _____________
_________________________
Hemophilia
Colorblindness
Duchenne Muscular Dystrophy
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Make a cross with an X-linked gene
Hemophilia is an ________________
________________ disease
X-linked
recessive
H
Use ______ for normal dominant blood
clotting gene. Use ______ for
recessive hemophilia gene. On X chromosome so
write it as ________
h
Xh
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• Mother
• 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
CARRIER
h h
H
h
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Make a cross with an X-linked gene
Carrier Mom X Normal dad
XH y
XH
Xh
GIRLS _______ normal _______ look normal
but are
CARRIERS BOYS _______ normal _______
hemophilia
1/2
XHXH XHy XHXh
Xh y
1/2
1/2
1/2
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Make a cross with an X-linked gene
Colorblindness is an ________________
________________ disease
X-linked
recessive
B
Use ______ for normal dominant color gene Use
______ for recessive colorblind gene. On X
chromosome so write it as ________
b
Xb
15

• Mother
• normal vision X X
• normal vision X X
• colorblind X X
• Father
• normal vision X y
• colorblind X y

B B
B b
CARRIER
b b
B
b
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Color blindness is sex linked
Xb y
XB
XB
HOMOZYGOUSNormal Mom X colorblind dad
XBXb XBy XBXb
XBy
GIRLS _______________ BOYS ________________
100 carriers
100 normal
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SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
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• Y linked genes ________ show up in males.
• X linked recessive genes appear __________ in
  males than females. WHY?
• Females can be __________ for X linked
  recessive traits.
• Males can _________ carriers for X linked
• recessive genes. The either have trait OR are
  normal.

ONLY
more often
CARRIERS
NEVER BE
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SEX INFLUENCED TRAITS

• Genes ___________ on sex chromosomes BUT affected
  by ____________ of individual with gene

not carried
sex hormones
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Male Pattern Baldness

• Autosomal dominant gene

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YOUR SEX CHANGES THE EXPRESSION OF THE GENE

• B is dominant for baldness
• B is recessive for not bald
• If you are MALE If you are FEMALE
• BB BB
• BB BB
• BB BB

BALD
BALD
BALD
NOT bald
NOT bald
NOT bald
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Will they be bald?
BX By
BX
BX
Bald B Autosomal Dominant gene
XXBB XyBB XXBB
XyBB
Bald dad X pure non bald mom
Girls 100 NOT BALD Boys 100 BALD
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Will they be bald?
BX By
BX
BX
Bald B Autosomal Dominant gene
XXBB XyBB XXBB
XyBB
NOT BALD dad X NOT BALD mom (who had
a bald dad)
Girls 100 NOT BALD Boys 50
BALD
50 NOT BALD
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How are genes passed on over generations?
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PEDIGREE CHART

• Males
• Females
• Has trait
• Carrier

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(No Transcript)
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SEX-LINKED and SEX
INFLUENCEDTRAITS
28
SEX DETERMINATION

• XX ___________

Xy _________
29
Who decides?
X
X

• Mom can give X
• Dad can give X or y

X
y
Dads determine sex of babies. If dad gives X
with moms X girl If dad give y with moms X
boy
30
SEX CHROMOSOMES CAN CARRY OTHER GENES TOO
___________________
31
SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
32
Sex chromosomes can carry other genes

• Y-LINKED GENES
• Genes carried on Y chromosome

EXHairy pinna
_________genes only show up in _______
33
Make a cross with a y-linked gene
Hairy ears is a ________________
________________ trait
Use ______ for hairy ears. Use ______ for
recessive normal ears. On y chromosome so write
it as ________
34
Make a cross with a y-linked gene
X
X
ALL GIRLS ____________
X
ALL BOYS ____________
yH

35
Sex chromosomes can carry other genes

• X-LINKED GENES Genes carried on the X chromosome

EX _____________ _____________
_________________________
36
Make a cross with an X-linked gene
Hemophilia is an ________________
________________ disease
Use ______ for normal dominant blood
clotting gene. Use ______ for
recessive hemophilia gene. On X chromosome so
write it as ________
37

• Mother
• Without hemophilia X X
• Without hemophilia X X
• With hemophilia X X
• Father
• Without hemophilia X y
• With hemophilia X y

38
Make a cross with an X-linked gene
Carrier Mom X Normal dad
XH y
XH
Xh
GIRLS _______ normal _______ look normal
but are
CARRIERS BOYS _______ normal _______
hemophilia

39
Make a cross with an X-linked gene
Colorblindness is an ________________
________________ disease
Use ______ for normal dominant color gene Use
______ for recessive colorblind gene. On X
chromosome so write it as ________
40

• Mother
• normal vision X X
• normal vision X X
• colorblind X X
• Father
• normal vision X y
• colorblind X y

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Color blindness is sex linked
Xb y
XB
XB
HOMOZYGOUSNormal Mom X colorblind dad

GIRLS _______________ BOYS ________________

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SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
43
Y 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.
The either have trait OR are normal.
44
SEX INFLUENCED TRAITS

• Genes ___________ on sex chromosomes BUT affected
  by ____________ of individual with gene

not carried
sex hormones
45
Male Pattern Baldness

• Autosomal dominant gene

46
YOUR SEX CHANGES THE EXPRESSION OF THE GENE

• B is dominant for baldness
• B is recessive for not bald
• If you are MALE If you are FEMALE
• BB BB
• BB BB
• BB BB

47
Will they be bald?
BX By
BX
BX
Bald B Autosomal Dominant gene

Bald dad X pure non bald mom

48
Will they be bald?
BX By
BX
BX
Bald B Autosomal Dominant gene

NOT BALD dad X NOT BALD mom (who had
a bald dad)

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How are genes passed on over generations?
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PEDIGREE CHART

• Males
• Females
• Has trait
• Carrier

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(No Transcript)
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Source Goshen Community High School