Download Examples of connected symbols:

11/20/2013
Genetics Unit
A
pedigree is a chart that shows which
members of a family have a certain trait.
Male without the trait
Male with the trait
Female without the trait
I.
1
2
3
4
Female with the trait
II.
1
2
3
4
5
6
7
III.
1
2
Examples of connected symbols:
 Marriage
Female (mom)
 Children

Fraternal twins

Identical twins
Male (dad)
Offspring
Female (mom)
Male (dad)
Offspring
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A
and B are grandparents.
Who are their children?
 What is the sex of their children?
 Do their children have the trait?

KEY
1
2
Normal male
Affected male
3
4
5
6
Normal female
A
B
C
D
E
F
G
H
Affected female
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 If
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9
10
11
12
a trait is DOMINANT
 Disorder: Achondroplasia
A = trait
 a = no trait
 Cause:
mutation in FGFR3 gene for protein
receptor on cells
 Symptoms: limited height, disproportionately
short arms and legs, large head due to
improper function of protein involved in
signaling to regulate bone growth
 Location: Chromosome 4

 If
I
a trait is RECESSIVE
A = no trait
 a = trait

 Achondroplasia
(dwarfism) is a
dominant disorder
 What would the
pedigree of the
family be?
Roloff Family
Pedigree
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 THIS
is WHY dwarfs
can have NORMAL
sized children…EVEN
twins
What would be the
genotype for each
individual in this
family?
aa
 Describe
the family in words
Aa
Aa
Aa
or
AA
aa
aa
 What
would the genotypes be if the trait is
dominant?
 A=
B=
C=
D=
B
A
C
A
B
C
D
D
 What
would the genotypes be if the trait is
dominant?
 A= aa
B= aa
C= Aa
D=aa
 What
would the genotypes be if the trait is
recessive?
 A=
B=
C=
D=
A
B
A
B
C
D
C
D
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 What
would the genotypes be if the trait is
recessive?
 A= Aa
B= Aa
C= aa
D= Aa
 Can
this be a dominant trait, a recessive
trait, or both?
 CAN “aa” have a child that is “Aa” or “AA”
A
B
A
B
C
D
C
D
 Can
this be a dominant trait, a recessive
trait, or both?
 RECESSIVE!!
A
 Dominant
or Recessive?
A
B
C
D
B
 Dominant
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 Dominant
or Recessive?
 Recessive
 Classify
pedigrees as autosomal dominant,
autosomal recessive, or sex-linked
 Males:
XY
 Females:
XX
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 1/10
males in the US cannot see the 16
females cannot see the 16
 1/100
 WHY
THE DIFFERENCE?
 Disorder:
colorblindness
Deleted genetic material in the gene
opsin 1 medium-wave-sensitive (OPN1MW)
that codes for the green color receptors
(cones)
 Location: X chromosome
 Cause:
 Sex-linked
genes are genes that are located
on the X-chromosome
 The human Y chromosome is much smaller
than the X chromosome and appears to
contain only a few genes.
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 Males
have just one X chromosome. Thus, all
X (sex-linked) alleles are expressed in males,
even if they are recessive.
 Colorblindness
is a sex-linked trait. A
colorblind man (XcY) marries a woman who is
heterozygous for colorblindness (XCXc). Which
of the following could NOT be a genotype of
their offspring?
XcY
XCXc
 XCXC
 XCY


 In
chickens, a dominant gene (F) on the X
chromosome results in silver feathers. Its
recessive allele (f) results in gold feathers.
What are the 2 possible F1 generations that
would result from a cross between a golden
rooster and a silver hen? (Hint: 2 possible
genotypes for a silver hen)
 Disorder:
hemophilia
lack of blood
clotting. No proteins
produced to properly clot
simple cuts
 Locations: X chromosome
 Symptoms:
 Husband
 Husband
 They
 They
was Albert (normal XY)
had 9 kids.
 Leopold was the only child with hemophilia,
why?
 Daughter: Beatrice was a carrier
 Daughter: Alice is a carrier as well. She
married Louis of Hesse. **Focus**
Louis of Hesse
had 6 kids
 Daughter: Irene was a carrier
 Son: Fred HAD hemophilia and died
 Daughter: Alix is a carrier. She married
Nikolas II of Russia **
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 Husband:
Nickolas II of Russia
had 5 kids
 4 girls and 1 boy
 Son: Alexis has hemophilia but was executed
at the age of 14 along with the rest of his
family.
 They
 Grand
Duchess Anastasia, Nickolas II
youngest daughter was believed to never
have been executed. Her body had never
been recovered, and who was believed by
some to have managed to survive the
revolution
Royalty of Great Britain
Future King of
England (no
hemophilia)
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 Pedigrees
are family trees that explain your
genetic history.
 Pedigrees are used to find out the probability
of a child having a disorder in a particular
family.
 To begin to interpret a pedigree, determine
if the disease or condition is autosomal or Xlinked and dominant or recessive.
A man and woman marry. They have five
children, 2 girls and 3 boys. The mother is a
carrier of hemophilia, an X-linked disorder. She
passes the gene on to two of the boys who died
in childhood and one of the daughters is also a
carrier. Both daughters marry men without
hemophilia and have 3 children (2 boys and a
girl).



Create a pedigree for the family describe. (Be sure
to shade individuals affected with hemophilia)
Determine the genotypes of the family members.
List the genotypes on your pedigree.
What is the chance the carrier daughter will have a
son with hemophilia?
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