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QOD
Who is Thomas Hunt Morgan?
What were his contributions to the
field of genetics?
Chapter 12: Inheritance Patterns
and Human Genetics
Section 1: Chromosomes and
Inheritance
Sex Determination and Sex
Linkage
Thomas Hunt Morgan
– Fruit flies (Drosophila)
Sex chromosomes
Sex linkage
– X-linked and y-linked
– Drosophila eye color
– Humans
Color blindness
Hemophelia
XX and YY
Chart
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Sex linkage
Linkage Groups
Linkage group
Morgan’s drosophila
– GGLL x ggll
F1 all heterozygous gray body, long wings
– GgLl x GgLl
Hypothesis: 3:1 ration Gray/long:black/short
Actual: neither 9:3:3:1, nor 3:1
Crossing-over
Chromosome Mapping
Chromosome map
– Alfred Sturtevant
– Frequencies of crossing-over
Map unit
Mutations
Germ-cell mutations
Somatic cell mutations
Lethal mutations
Chromosome
Gene
Chromosome Mutations
Insertion
Deletion
Inversion
Translocation
Nondisjunction
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Gene Mutations
Point mutations
– Substitution
– Frameshift mutations
Insertion
Deletion
Gene Mutations
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QOD
What is a polygenic trait?
Examples? Describe the
phenotypic ranges resulting from
this inheritance.
Chapter 12: Inheritance Patterns
and Human Genetics
Section 2: Human Genetics
PedigreeHuntington
Disease
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Genetic Disorders Caused by
Single Allele
Dominant
– Huntington’s disease
– Polydactyly
Recessive
– Albinism
– Cystic fibrosis
– Phenylketonuria
– Tay-Sachs
Codominance
Sickle Cell Disease
– Homozygous sickle cell  disorder
– Change in hemoglobin – protein in RBC’s that
carry oxygen/carbon dioxide
– Heterozygous:
– Heterozygous individuals have advantage
Multiple Alleles
Blood types
Three alleles
– IA = A type
– IB = B type
– I = O type
– Also shows codominance
ABO Blood
GroupSurface Pro A
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ABO Blood
GroupSurface Pro B
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ABO Blood
GroupSurface Pro
B-B
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ABO Blood
GroupNo Surface
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Blood Types
Type Alleles Antigens Antibodies
A
B
AB
O
Accepts Donates
to:
Blood Types
Type Alleles Antigens Antibodies
A
IA IA , IA i A
B
B
IB IB , IB i B
A
AB
IA IB
A and B
None
O
ii
None
Accep Donates
ts
to:
A, O
A, AB
B, O
A, B,
AB, O
A and B O
B, AB
AB
A, B,
AB, O
Blood types
IA and IB are codominant to eachother
IA and IB are dominant to I
Type AB is known as the “Universal
Acceptor”
Type O is known as the “Universal donor”
QOD
How can we detect genetic
disorders in a fetus?
Sex-Linked Traits
Muscular dystrophy
Color-blindness
Hemophelia
Different from sex-influenced traits
Polygenic Inheritance
Range in phenotypes
Examples:
– Height
– Eye color
– Skin color
Number of
Genes
Involved in
Skin Color
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Abnormal Numbers of
Chromosomes
How?
Nondisjunction
– Monosomy
– Trisomy
– Polyploidy
– Down syndrome
Detecting Genetic Disorders
Genetic counseling
Amniocentesis
Chorionic villi sampling
Karyotyping
Karyotype 1
Karyotype 2
Turner’s Syndrome
Klinefelter’s Syndrome
Karyotype 4