SEX-LINKED and SEX INFLUENCED TRAITS

1
SEX-LINKED and SEX
INFLUENCEDTRAITS
2
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
5
SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
6
Sex chromosomes can carry other genes

• Y-LINKED GENES
• Genes carried on Y chromosome

EXHairy pinna
Y linked
males.
_________genes only show up in _______
7
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
8
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
9
Sex chromosomes can carry other genes

• X-LINKED GENES Genes carried on the X chromosome

EX _____________ _____________
_________________________
Hemophilia
Colorblindness
Duchenne Muscular Dystrophy
10
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
11

• 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
12
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
13
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
14

• 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
15
Color blindness is sex linked
Xb y
XB
XB
HOMOZYGOUSNormal Mom X colorblind dad
XBXb XBy XBXb
XBy
GIRLS _______________ BOYS ________________
100 carriers
100 normal
16
SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
17
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.
ONLY
more often
CARRIERS
NEVER BE
18
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
23
How are genes passed on over generations?
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PEDIGREE CHART

• Males
• Females
• Has trait
• Carrier

25
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26
SEX-LINKED and SEX
INFLUENCEDTRAITS
27
SEX DETERMINATION

• XX ___________

Xy _________
28
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
29
SEX CHROMOSOMES CAN CARRY OTHER GENES TOO
___________________
30
SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
31
Sex chromosomes can carry other genes

• Y-LINKED GENES
• Genes carried on Y chromosome

EXHairy pinna
_________genes only show up in _______
32
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 ________
33
Make a cross with a y-linked gene
X
X
ALL GIRLS ____________
X
ALL BOYS ____________
yH

34
Sex chromosomes can carry other genes

• X-LINKED GENES Genes carried on the X chromosome

EX _____________ _____________
_________________________
35
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 ________
36

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

37
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

38
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 ________
39

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

40
Color blindness is sex linked
Xb y
XB
XB
HOMOZYGOUSNormal Mom X colorblind dad

GIRLS _______________ BOYS ________________

41
SEX LINKED TRAITS show up in different in
males and females because they move with the sex
chromosomes
42
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.
43
SEX INFLUENCED TRAITS

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

not carried
sex hormones
44
Male Pattern Baldness

• Autosomal dominant gene

45
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

46
Will they be bald?
BX By
BX
BX
Bald B Autosomal Dominant gene

Bald dad X pure non bald mom

47
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)

48
How are genes passed on over generations?
49
PEDIGREE CHART

• Males
• Females
• Has trait
• Carrier

50
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