Transcript Sex-Linked Traits By: Lauren Beggs Agenda 2/26/2013  Turn in 7.2 KT’s and questions 1-6    7.2 KT’s and questions 1-6 Incomplete Dominance Wkst HW: Read 7.1,

Sex-Linked Traits
By: Lauren Beggs
Agenda 2/26/2013
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Turn in 7.2 KT’s and questions 1-6
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7.2 KT’s and questions 1-6
Incomplete Dominance Wkst
HW: Read 7.1, KT’s, and questions 1-5
Bellringer 2/26/2013
Shh! Don’t tell your answer.
 Can you see a number in
this picture? If so… what
number do you see?
Estimated:
 1/10 Caucasian males are
colorblind
 1/20 Caucasian females
are colorblind.
Why is color-blindness
more prevalent in
males than in
females?
Sex-Linked Traits
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Mendel only studied traits on autosomes.
Autosomes: only
contain genes unrelated
to the sexual characteristics
of an organism
Sex Chromosomes:
contain genes that
code for the sexual
characteristics of an
organism
Sex-Linked Traits
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Sex-Chromosomes
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Females = XX
Males = XY
female
male
There are thousands more genes on the
X chromosome than the Y chromosome.
Who determines the sex of the child?
Mom or dad?
Sex-Linked Traits
Mom
Dad
Diploid Parent Cell
XY
XX
X
X
Haploid
Gametes
X
Y
Sex-Linked Traits
#1
Egg
Sperm
X
Offspring:
#2
Egg
Offspring:
X
XX
Sex of the child?
Sperm
Y
X
XY
Sex of the child?
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Sex-Linked Genes: Genes located on
the sex chromosomes.
Sex-Linked Traits
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Calico is coat fur color found in cats,
which is caused by a SEX-LINKED,
CODOMINANT allele.
B = Black
R = oRange
BR = calico
calico cat
Sex-Linked Traits
Female genotypes, phenotypes?
 XBXB ______________
 XBXR ______________
R R
 X X ______________
Male genotypes, phenotypes?
 XBY ______________
calico cat
 XRY ______________
Sex-Linked Traits
Female genotypes, phenotypes?
 XBXB -- Black
 XBXR -- Calico
 XRXR -- Orange
Male genotypes, phenotypes?
B - X Y Black
 XRY -- Orange
calico cat
Sex-Linked Traits
A black male cat is crossed with an
orange female cat.
x
Predict the phenotypes and genotypes of the offspring
for both males AND females.
Sex-Linked Traits
Male: XBY
x
Female: XRXR
Predict the phenotypes and genotypes of the offspring
for both males AND females.
Sex-Linked Traits
Male: XBY
XR
x
XB
Y
XR XB
XR Y
Female: XRXR
100% Females = calico
100% Males = orange
XR
XR XB
XR Y
Sex-Linked Traits
An orange male cat is crossed with an
calico female cat.
x
Predict the phenotypes and genotypes of the offspring
for both males AND females.
Sex-Linked Traits
Male: XRY
x
Female: XRXB
Predict the phenotypes and genotypes of the offspring
for both males AND females.
Sex-Linked Traits
Male: XRY
x
XR
Y
XR
XR XR
XR Y
XB
XR XB
XB Y
Female: XRXB
50% Females = calico
50% Females = orange
50% Males = orange
50% Males = black
…Food for Thought
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If almost 10% of the
population can’t
differentiate between red &
green…than why is the
“stop” and “go” on a traffic
light red and green?!