Test 2 Test 2 Thursday Nov. 17Thursday Nov. 17
Quiz 4 answersQuiz 4 answers
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Wed. 1:15 – 2:15Wed. 1:15 – 2:15
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Mendelian GeneticsMendelian Genetics
Topics:Topics: -Transmission of DNA during cell division-Transmission of DNA during cell division
Mitosis and MeiosisMitosis and Meiosis
- Segregation - Segregation
- Sex linkage (- Sex linkage (problem: how to get a white-eyed femaleproblem: how to get a white-eyed female))
- Inheritance and probability- Inheritance and probability
- Independent Assortment- Independent Assortment
- Mendelian genetics in humans- Mendelian genetics in humans
- Linkage- Linkage
- Gene mapping- Gene mapping
-Gene mapping in other organismsGene mapping in other organisms
(fungi, bacteria)(fungi, bacteria)
- Extensions to Mendelian Genetics- Extensions to Mendelian Genetics
- Gene mutation- Gene mutation
- Chromosome mutation- Chromosome mutation
(- Quantitative and population genetics)(- Quantitative and population genetics)
B2900B2900
MutationMutation
Source of genetic variation:Source of genetic variation:
Gene Mutation Gene Mutation
- somatic, germinal- somatic, germinal
Chromosome mutations (Ch. 11)Chromosome mutations (Ch. 11)
- structure - structure (deletion, duplication, inversion, translocation)(deletion, duplication, inversion, translocation)
- number- number
Chromosome MutationChromosome Mutation(2. changes in number)(2. changes in number)
Euploidy: Euploidy: variation in complete sets ofvariation in complete sets of
chromosomeschromosomes
Aneuploidy: Aneuploidy: variation in parts of chromosomevariation in parts of chromosome
setssets
EuploidyEuploidy
1x 1x monoploid (1 set) = n monoploid (1 set) = n
2x 2x diploid (2 sets) = 2ndiploid (2 sets) = 2n
3x triploid3x triploid
4x tetraploid4x tetraploid
5x pentaploid 5x pentaploid polyploid (> polyploid (> 22 sets) sets)
6x hexaploid6x hexaploid
n = # chromosomes n = # chromosomes
in the gametesin the gametes
2n2n 4n4n
PolyploidsPolyploids
Autopolyploids: Autopolyploids: within one specieswithin one species
Allopolyploids: Allopolyploids: from different, closelyfrom different, closely
related speciesrelated species
PolyploidsPolyploids
Larger Larger than Diploidsthan Diploids
PolyploidsPolyploids
Triploids: = 3nTriploids: = 3n
- problems with pairing during- problems with pairing during
meiosismeiosis
- unbalanced gametes- unbalanced gametes
- usually steril- usually sterilee
Applications:Applications: seedless fruits, sterile fish seedless fruits, sterile fish
aquacultureaquaculture
Formation of TriploidsFormation of Triploids
nn
nn
nn
= = 3n3n
nn
PolarPolarbodiesbodies
nn 22nnnn
= = 3n3n
Triploids (3x)Triploids (3x)
Why can’t a triploid produce viable Why can’t a triploid produce viable gametes ?gametes ?
Fig. 11-5
Triploids (3x)Triploids (3x)
x = 1x = 1 GametesGametes
TriploidsTriploids
x = 2x = 2
GametesGametes
oror
viableviable
Non-Non-viableviable
Viable Gametes from TriploidsViable Gametes from Triploids
Probability Probability
(2x or x gamete) =(2x or x gamete) =
( )( )if x = 10 Prob. = 0.002 if x = 10 Prob. = 0.002
of viable gametesof viable gametes
11
22
x - 1x - 1
0
0.1
0.2
0.3
0.4
0.5
0 5 10 15 20 25 30 35
Number of Chromosomes
Pro
babi
lity
of V
iabl
e G
amet
es
# of chrs2
3
4
Triploid FishTriploid FishFrankenfish-Biotech
3n carp3n carp
AutotetraploidAutotetraploid
AutotetraploidAutotetraploid
Doubling of chromosomes: 2x----> 4xDoubling of chromosomes: 2x----> 4x
Even number of chromosomes: normal meiosisEven number of chromosomes: normal meiosis
2<---->2 segregation------> functional 2<---->2 segregation------> functional gametesgametes
PolyploidsPolyploids
Autopolyploids: Autopolyploids: within one specieswithin one species
Allopolyploids: Allopolyploids: from different, closelyfrom different, closely
related speciesrelated species
HybridizationHybridization
Triploid
2n = 42 x = 7
n = 21
2n = 14, n = x = 7
Chromosome sets:
A, B, D
7 7 7
hybrid
Origin of Origin of WheatWheat
Fig. 11-10Fig. 11-10
2n = 28
n = 14
77 1414
AllopolyploidAllopolyploid
PolyploidyPolyploidy
Plants: speciation (wheat) Plants: speciation (wheat)
Animals: - rare (sex determination)Animals: - rare (sex determination)
- fish- fish (salmon: tetraploid) (salmon: tetraploid)
- - parthenogenetic parthenogenetic animalsanimals
123 11 22 12 12
Latitute North
30 40 50 60 70 80 90
% P
olyp
loid
s
30
40
50
60
70
80
90Plant PolyploidsPlant Polyploids
Chromosome MutationChromosome Mutation((changes in number)changes in number)
Euploidy: Euploidy: variation in complete sets ofvariation in complete sets of
chromosomeschromosomes
Aneuploidy: Aneuploidy: variation in parts of chromosomevariation in parts of chromosome
setssets
AneuploidyAneuploidy
Nullisomics (2n - 2)Nullisomics (2n - 2)
Monosomics (2n - 1)Monosomics (2n - 1)
Trisomics (2n + 1)Trisomics (2n + 1)
normalnormal
AneuploidyAneuploidy
Nullisomics (2n - 2)Nullisomics (2n - 2)
- lethal in diploids- lethal in diploids
- tolerated in polyploids- tolerated in polyploids
Monosomics (2n - 1)Monosomics (2n - 1)
- disturbs chromosome balance- disturbs chromosome balance
- recessive lethals hemizygous- recessive lethals hemizygous
Trisomics (2n + 1)Trisomics (2n + 1)
- sex chromosomes vs autosomes- sex chromosomes vs autosomes
- size of chromosome- size of chromosome
AneuploidyAneuploidy
Non-disjunction: GametesNon-disjunction: Gametes
Meiosis I n + 1 n - 1Meiosis I n + 1 n - 1
Meiosis II n + 1 n - 1 Meiosis II n + 1 n - 1 nn
n x n - 1 ---------> 2n - 1 monosomicn x n - 1 ---------> 2n - 1 monosomic
n x n + 1 ---------> 2n + 1 trisomicn x n + 1 ---------> 2n + 1 trisomic
Human AneuploidsHuman Aneuploids
1318
21 X Y
AneuploidyAneuploidyHumans:Humans: (live births) (live births)
Monosomics - XO Turner syndromeMonosomics - XO Turner syndrome
- no known autosomes- no known autosomes
Trisomics XXY Trisomics XXY KKlinefelter sterile malelinefelter sterile male
XYY fertile maleXYY fertile male ( X or Y gametes)( X or Y gametes)
XXX sometimes normalXXX sometimes normal
21 Down21 Down
18 Edwards syndromes18 Edwards syndromes
13 Patau13 Patau
Maternal Age (years)
20 25 30 35 40 45 50
Dow
ns B
irths
per
100
0
0
5
10
15
20
25Downs Births per 1000Downs Births per 1000
2 %
0.62 % 50 %
Mutations Causing Death and Mutations Causing Death and Disease in HumansDisease in Humans
% of live births% of live births
Gene mutations: Gene mutations: 1.2 1.2
Chromosome mutationsChromosome mutations:: 0.610.61
Chromosome MutationsChromosome Mutations(Humans)(Humans)
% of spontaneous abortions% of spontaneous abortions
Trisomics 26 %Trisomics 26 %
XO 9 %XO 9 %
Triploids 9 %Triploids 9 %
Tetraploids 3 %Tetraploids 3 %
Others 3 %Others 3 %
Chromosome 50 %Chromosome 50 %
abnormalitiesabnormalities
Chromosome MutationsChromosome Mutations
Comparison of euploidy with aneuploidyComparison of euploidy with aneuploidy
Aneuploids more abnormal than euploids:Aneuploids more abnormal than euploids:
likely due to gene imbalancelikely due to gene imbalance
Plants more tolerant than animals to Plants more tolerant than animals to aneuploidy and polyploidyaneuploidy and polyploidy
(animal sex determination)(animal sex determination)
SummarySummaryMutationMutation - gene - gene
- chromosome- chromosome
(structure, number)(structure, number)
DetectingDetecting - cytology - cytology
- phenotype- phenotype
Rate of mutationRate of mutation - low - low
MutationMutation - source of genetic variation - source of genetic variation
- evolutionary change- evolutionary change
geneticgeneticanalysisanalysis
Chapter Chapter ReferencesReferencesMitosis and MeiosisMitosis and Meiosis
Ch. 4 p. 100 – 112 Prob: 10, 11, 12, 18, 19Ch. 4 p. 100 – 112 Prob: 10, 11, 12, 18, 19
Mendelian InheritanceMendelian Inheritance
Ch. 5 p. 118 – 129 Prob: 1 – 3, 5, 6, 7, 8, 9Ch. 5 p. 118 – 129 Prob: 1 – 3, 5, 6, 7, 8, 9
RRecombinationecombination, l, linkage mapsinkage maps
Ch. 6 p. 148 – 165 Prob: 1-5, 7, 8, 10, 11, 14Ch. 6 p. 148 – 165 Prob: 1-5, 7, 8, 10, 11, 14
Extensions to Mendelian GeneticsExtensions to Mendelian Genetics
Ch. 14 p. 459 – 473 Prob: 2, 3, 4, 5, 6, 7Ch. 14 p. 459 – 473 Prob: 2, 3, 4, 5, 6, 7
Chromosome MutationsChromosome Mutations
Ch. 11 p. 350 – 377 Prob: 1, 2Ch. 11 p. 350 – 377 Prob: 1, 2
Mendelian GeneticsMendelian Genetics
Topics:Topics: -Transmission of DNA during cell division-Transmission of DNA during cell division
Mitosis and MeiosisMitosis and Meiosis
- Segregation - Segregation
- Sex linkage- Sex linkage
- Inheritance and probability- Inheritance and probability
- Independent Assortment- Independent Assortment
- Mendelian genetics in humans- Mendelian genetics in humans
- Linkage- Linkage
- Gene mapping- Gene mapping
-Gene mapping in other organismsGene mapping in other organisms
(fungi, bacteria)(fungi, bacteria)
- Extensions to Mendelian Genetics- Extensions to Mendelian Genetics
- Gene mutation- Gene mutation
- Chromosome mutation- Chromosome mutation
GeneticsGenetics
Part I Part II Part I Part II
Molecular MendelianMolecular Mendelian
Chromosome Theory of Chromosome Theory of InheritanceInheritance
- - genes organized into chromosomesgenes organized into chromosomes
- - correlation: correlation: Genetics & CytologyGenetics & Cytology
- theory can explain segregation and- theory can explain segregation and
independent assortmentindependent assortment
Two Two typestypes of nuclear division of nuclear division
1. Mitosis (somatic tissue)1. Mitosis (somatic tissue)
2. Meiosis (germ tissue)2. Meiosis (germ tissue)
Mendelian GeneticsMendelian Genetics
• Meiosis and mitosis Meiosis and mitosis
• Segregation and independent assortmentSegregation and independent assortment
• Sex linkage, sex determinationSex linkage, sex determination
• PedigreesPedigrees
• Linkage, recombination and linkage mapsLinkage, recombination and linkage maps
Mendelian GeneticsMendelian Genetics
• Gene linkage: 3 point test cross, tetrad analysisGene linkage: 3 point test cross, tetrad analysis
• Extensions Extensions (dominance, multiple alleles, pleiotropy, (dominance, multiple alleles, pleiotropy, epistasis,epistasis,
penetrance and expressivity)penetrance and expressivity)
• Mutation: gene mutation Mutation: gene mutation
chromosome mutation (numberchromosome mutation (number
structure)structure)
Mendelian GeneticsMendelian Genetics
ApplicationsApplications
Genetic markers as tools:Genetic markers as tools:
- human diseases- human diseases
- population genetics- population genetics
- genetic structure (gene flow)- genetic structure (gene flow)
- systematics and phylogeny- systematics and phylogeny
- forensics- forensics
Mendelian Genetics Mendelian Genetics in Humansin Humans
Determining mode of inheritanceDetermining mode of inheritance
Problems:Problems:
1. long generation time1. long generation time
2. can not control matings2. can not control matings
Alternative:Alternative:
* information from matings that have * information from matings that have already occurred “already occurred “PedigreePedigree” ”
Human PedigreesHuman Pedigrees
Pedigree analysis:Pedigree analysis:
• trace inheritance of disease or conditiontrace inheritance of disease or condition
• provide clues for mode of inheritanceprovide clues for mode of inheritance
• however, some pedigrees ambiguoushowever, some pedigrees ambiguous
Human PedigreesHuman Pedigrees
Pedigree analysis:Pedigree analysis:
dominant vs recessivedominant vs recessive
autosomal vs sex linkedautosomal vs sex linked
Linkage: Linkage: Human Genetic DiseasesHuman Genetic Diseases
Linkage:Linkage:
• organization of genes and genomeorganization of genes and genome
• marker genes linked to:marker genes linked to:
Disease genes Disease genes
MutationMutation
Gene MutationGene Mutation
- somatic, germinal- somatic, germinal
- detecting mutations- detecting mutations
Chromosome mutationsChromosome mutations
- structure- structure
- number- number
Chromosome MutationChromosome Mutation(changes in number)(changes in number)
Euploidy: Euploidy: variation in complete sets ofvariation in complete sets of
chromosomeschromosomes
Aneuploidy: Aneuploidy: variation in parts of chromosomevariation in parts of chromosome
setssets
Careers in GeneticsCareers in Genetics
cytogeneticscytogenetics
molecular geneticsmolecular genetics
human geneticshuman genetics
population geneticspopulation genetics
quantitative geneticsquantitative genetics
developmental geneticsdevelopmental genetics
immunogeneticsimmunogenetics
etc. etc.etc. etc.
Genetics Courses Genetics Courses
B2900 Principles of Evolution and SystematicsB2900 Principles of Evolution and Systematics
B2060 Principles of Cell BiologyB2060 Principles of Cell Biology
B3530 Developmental BiologyB3530 Developmental Biology
B4241 Advanced GeneticsB4241 Advanced Genetics
B4250 Evolutionary GeneticsB4250 Evolutionary Genetics
B4900 BiotechnologyB4900 Biotechnology
Honours Thesis Research in GeneticsHonours Thesis Research in Genetics
Announcement
NSERC
Undergraduate Student Research Awards (USRA) in
Universities
16 weeks $5,625
www.nserc.ca
MUN deadline Early Jan, 2006
