Overview: Genetic Mapping

1
Overview Genetic Mapping
Basic Principles
Genes, RFLPs, SNPs Meiosis, Independent
Assortment, Linkage and Crossing Over
Genetic Mapping in Experimental Organisms
Two- and Three-point crosses Complementation
Analysis
Genetic Mapping in Humans
Pedigree Analysis
2
Function of Human Genes
Fig. 20-13 Pg. 497
3
Genetic Map of Drosophila
Fig. 5-14
4
Gametes (haploid cells)
Fig. 2-8
5
Crossing Over Occurs Between DNA of Homologous
Chromosomes
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Pairing of Homologous Chromosomes
Fig. 2-13, 2-14
7
Crossing Over Occurs Between DNA of Homologous
Chromosomes
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Drosophila melanogaster (Fruit Fly)
9
Drosophila melanogaster (Fruit Fly)

• Phenotypes
• eye color
• body color
• wing shape
• antenna length
• bristle pattern

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Recessive Allele
Dominant Allele (WT)
Gene Name
se
se
Sepia Eyes
cu
cu
Curled Wings
sr
sr
Striped Body
jv
jv
Javelin Bristles
11
Double Crossover (DCO)
Paternal
Paired Homologous Chromosomes
Maternal
DCO Products
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February 2007
1168 Family Pedigrees with at least two ASD
individuals
13
Neurexin Proteins
14
Pedigree for Inheritance of Blood Type and
Nail-Patella Syndrome
15
Pedigree for Inheritance of ASD and a DNA Marker
I
II
Gel Electrophoresis
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Chromosome 11
Band 11q13
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Population Genetics (Chapter 25)
Mendelian Genetics Applied to Populations
The Hardy-Weinberg Equation (p2 2pq q2)
Test populations for microevolution Estimate
frequency of carriers for recessive genetic
disorders Assess effect of natural selection and
mutation on microevolution Assess effect of
inbreeding DNA Profiling (DNA fingerprinting)
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HIV-1 Structure
(Gp120)
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HIV Infection Pathway
HIV-1
Extra-cellular Space
Gp120
CD4
Membrane
CCR5
Cytosol
Protein encoded by CCR5-1 allele (CCR5-1 / CCR5-1
or CCR5-1 / CCR5-?32)
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CCR5 RFLP
CCR5-1
CCR5-?32
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CCR5 Genotype Analysis
Fig. 25-3
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CCR5-?32 Allele Frequency
Fig. 25-4
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Assumptions of the Hardy-Weinberg Equation

• Individuals of all genotypes have equal rates of
  survival and
• reproductive success (no selection).

• No new alleles are created or converted from one
  allele to
• another by mutation.

• Individuals do not migrate into or out of the
  population
• (no gene flow).

• The population is infinitely large (no genetic
  drift).

• Individuals in the population mate randomly (no
  inbreeding)

Page 619-620
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25
Effect of Selection on Allele Frequency
Fig. 25-7
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Changes in CCR5-?32 Allele Frequency
Fig. 25-8
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Fibroblast Growth Factor 3 (FGFR3) Receptor
840 amino acids
2520 bp ORF
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FGFR3 Signal Transduction Pathways
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Fibroblast Growth Factor 3 (FGFR3) Receptor
A
G
(Gly to Arg)
C
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DELAYED LYSOSOMAL DEGREDATION
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Homozygosity as a Function of Inbreeding
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Tandem Repeat Locus
GTCTAG GTCTAG GTCTAG GTCTAG CAGATC CAGATC CAGATC
CAGATC
(a.k.a VNTR, STR, Microsatellite)
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Chromosome 7
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GTCTAG GTCTAG GTCTAG CAGATC CAGATC CAGATC
7M
GTCTAG GTCTAG GTCTAG GTCTAG CAGATC CAGATC CAGATC
CAGATC
7P
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RFLP Analysis of VNTR Loci
Fig. 22-27