Ch.11

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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Sometimes inheritance does not follow Mendels
rules (Non-Mendelian Genetics)
X

X

X

X

Eye Color
Skin Tone
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Incomplete Dominance
The heterozygous phenotype is a blend of the
dominant and recessive
R
R
r
Rr
Rr
r
Rr
Rr
r
R
R
Rr
RR
r
Rr
rr
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Codominance
Both alleles are expressed
rr
R
R
RR
r
Rr
Rr
r
Rr
Rr
Rr
Rr
Rr
Rr
r
R
R
rr
Rr
RR
RR
r
Rr
Rr
rr
Rr
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Codominance
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Population with a high risk of contracting Malaria
Population affected with Sickle Cell Anemia
Malaria Animation
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Multiple Alleles
There are more than 2 alleles for a particular
trait
For blood type in humans there are 3
alleles A B O (ABO blood type) A B are
Co-Dominant O is Recessive
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Can Receive From
Blood Types
Can Give to
Antigen
Antibody
Type A
B
A
A AB
A O
B
A
B AB
Type B
B O
Type AB
All
AB
none
A B
Type O
A B
All
none
O
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
What are the possible blood types for the
children of a heterozygous type A woman and a
heterozygous type B man?
Genotype
Phenotype
IA IA or IA i
Type A
IB IB or IB i
Type B
i
IA
IB i
IA IB
IB
Type AB
IA IB
i
i i
IA i
Type O
i i
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
What are the possible blood types for the
children of a heterozygous type A woman and a
heterozygous type B man?
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Polygenic Traits
more than one pair of genes code for a particular
trait ---------------------- The occurrence of
the phenotypes of a polygenic trait usually form
a bell curve
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Sex determination in humans
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Sex determination in humans
XX x XY
X
Y
X
XX
XY
X
XX
XY
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Sex-Linked Traits
Traits found on the sex chromosomes More traits
are found on the X-chromosome than the Y
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Sex-Linked Traits
Red-green colorblindness and hemophilia are
x-linked, recessive disorders
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Ch.11 Complex Inheritance Human Heredity
11.2 Complex Patterns of Inheritance
Sex-Linked Traits
Females are far less likely to have an x-linked
recessive disorder.
Y
XB
A cross between a carrier female and a male with
normal vision will lead to the following
XB
XBXB
XBY
Xb
XBXb
XbY
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
Genetic Disorders
Autosomal Recessive Disorders.
Defective membrane protein leads to digestive
Respiratory failures
Cystic Fibrosis
Little to no melanin production which causes skin
and eye damage from UV rays
Albinism
Inability to break down fatty substances leads to
a buildup in the brain and mental disabilities
Tay-Sachs
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
Genetic Disorders
Autosomal Dominant Disorders.
Huntingtons
Decline of mental and neurological function
Achondroplasia
Dwarfism
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
Pedigree Analysis
(Inter-family)
(The subject being studied)
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
Which shows a dominant and which a recessive
autosomal disorder?
Recessive
Dominant (or recessive)
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
Sex-Linked Recessive
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
What are the genotypes for I-1 I-2? II-1
II-2? III-1, III-2 III-3?
Aa
Aa
A?
A?
A?
aa
A?
Aa
Aa
Aa
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Ch.11 Complex Inheritance Human Heredity
11.1 Human Heredity
When carriers are shown on a pedigree you know
all genotypes (sometimes carriers are shown
sometimes they are not)
XAXa
XAY
XAXA
XaY
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Ch.11 Complex Inheritance Human Heredity
11.3 Chromosomes Human Heredity
Chromosomal Disorders
Down Syndrome
Kleinfelters Syndrome
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Ch.11 Complex Inheritance Human Heredity
11.3 Chromosomes Human Heredity
Nondisjunction
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Ch.11 Complex Inheritance Human Heredity
11.3 Chromosomes Human Heredity
Trisomy will usually cause death very early in
pregnancy.
Trisomy 13,15,18, 22 have been documented (most
die before age 1)
Trisomy 21
Down Syndrome
abnormal facial appearance, high likelihood of
mental retardation (degree varies considerably),
and increased likelihood of developing leukemia
and Alzheimers disease
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Ch.11 Complex Inheritance Human Heredity
11.3 Chromosomes Human Heredity
Nondisjunction in Sex Chromosomes
Klinefelters Syndrome Underdeveloped
reproductive organs infertility. May also
cause Enlarged breasts a decrease in mental
function.
Turners Syndrome Underdeveloped reproductive
organs infertility. Short stature and decreased
mental function