Genetik_10 Gene mutations_WS2015/2016.key

Einführung in die Genetik
Prof. Dr. Kay Schneitz (EBio Pflanzen)
http://plantdev.wzw.tum.de
[email protected]
Twitter: @PlantDevTUM, #genetikTUM
FB: Plant Development TUM
Prof. Dr. Claus Schwechheimer (PlaSysBiol)
http://wzw.tum.de/sysbiol
[email protected]
Einführung in die Genetik - Inhalte
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Einführung
Struktur von Genen und Chromosomen
Genfunktion
Transmission der DNA während der Zellteilung
Vererbung von Einzelgenveränderungen
Genetische Rekombination (Eukaryonten)
Genetische Rekombination (Bakterien/Viren)
Rekombinante DNA-Technologie
Kartierung/Charakterisierung ganzer Genome
Genmutationen: Ursache und Reparatur
Regulation der Genexpression
Genetische Analyse biologischer Prozesse
Transposons bei Eukaryonten
Veränderungen der Chromosomen
Regulation der Zellzahl - Onkogene
13. 10. 15
20. 10. 15
27. 10. 15
03. 11. 15
10. 11. 15
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24. 11. 15
01. 12. 15
08. 12. 15
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12. 01. 16
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26. 01. 16
02. 02. 16
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Mapping and characterization
of entire genomes
Genetics 09
Based on Chapter 15 (Griffiths; 10th ed.)
Summary •
Genome sequencing
• Large insert vectors
• YAC 100 - 300 kB
• BAC 50 - 2000 kB
• Phage lambda 35 - 45 kB
• Small insert vectors
• Plasmids (pBR322, pUC18/19) < 10 - 15 kB
• Insert size for sequencing 500 - 1000 bp
• Minimal tiling path
• Paired-end reads
• Genome sizes
• Chromosomes and chromosome numbers
• Exons and introns
• Synteny
• Bioinformatics (conserved sequences, exon/intron
precictions, cDNAs, ESTs, open reading frames)
Structure of a eukaryotic gene
Elements and sites be recognized by more or less conserved DNA sequence
elements, can therefore be predicted by bioinformatics
Exon/intron structure particularly important because it allows to predict the
sequence of a protein
Making gene predictions based on genome sequence
How does the availability of genome
sequences affect biological analyses?
Functional studies - Gene knock outs
Functional studies - Gene targeting
Functional studies - Gene targeting
Functional studies - Insertion mutagenesis
Transcriptomics and gene expression profiling
Microarrays
Heat map
Summary
• Next generation sequencing
• sequencing without cloning and ordering
• massive parallel sequencing
• 1000 genomes project
• Functional genomics (examples)
• Gene knock-outs (mammals, yeasts etc.)
• Gene targeting (mammals)
• Random insertion mutagenesis (T-DNA, plants)
• Transcriptomics (Microarrays, gene chips)
Gene mutations: their causes
and repair mechanisms
Genetics 10
Based on Chapter 17 (Griffiths; 10th ed.)
Types of gene mutations
Spontaneous mutations
Induced mutations
Quantitating mutagenicity and cancerogenicity
Biological repair mechanisms
Mutations and cancer
Types of gene mutations
Structure of a eukaryotic gene
Gene mutations - point mutations
Transition
G:C -> A:T
A:T -> G:C
C:G -> T:A
T:A -> C:G
Transversion
G:C -> T:A
G:C -> C:G
T:A -> A:T
T:A -> G:C
etc.
Gene mutations - insertions and deletions (Indels)
Indel mutations and replication slippage
Mutations can affect splicing
Effects of point mutations on
transcript and protein
Spontaneous mutations
Luria-Delbrück’s fluctuation test mutations normally occur spontaneously and randomly
Sequencing spontaneous mutations with
Next Generation Sequencing
Indel mutations and replication slippage
Mechanisms of spontaneous mutations
Mechanisms of spontaneous mutationsrare tautomeric form can induce mismatch
pairings
C* -> A
T* -> G
C -> A*
T -> G*
Manifestation of a mismatch
Spontaneous lesions - depurination
Spontaneous lesions - deamination
G:C -> A:T
Sequencing spontaneous mutations with
Next Generation Sequencing
Spontaneous lesions - oxidative damage
blocks replication
G:C -> T:A
Trinucleotide repeat mutations in humans:
e.g. the FMR-1 gene in Fragile X syndrome
Slipped mispairing explains the expansion of
trinucleotide repeats
Trinucleotide repeat diseases
Induced mutations
Base analogs (5-BU)
5-Bromouracil (5-BU)
5-BU:A -> C:G
Base analogs (2-AP)
2-Aminopurine (2-AP)
2-AP (A):T -> G:C
Alkylating agents
O
C2H5 O S CH3
O
Ethyl methanesulfonate
Intercalating agents
UV-light induced photoproducts
“Natural” carcinogens - aflatoxins
Aspergillus fumigatus
Quantitating mutagenicity and
carcinogenicity
Ames test
Ames test - classifying the mechanisms
TA100 - sensitive to
reversion through base pair
substitution
TA1535 and TA1538 sensitive to reversions
through frame shift
mutation
Biological repair mechanisms
Photolyases repair UV-induced photodimers
Homology-dependent repair - base excision repair
apurinic/apyrimidinic endonuclease
deoxyribophosphodiesterase
Homology-dependent repair - GGR and NER
Homology-dependent repair - GGR and NER
Xeroderma pigmentosum - Mutants in TFIIH
Mutations and cancer
Mutations can induce cancer
The ras oncogene
What you need to know and understand
for the exam and for your life....
... indels
... types of spontaneous mutations
... examples for induced mutations
... repair mechanisms
... Ames test
The end