Download point mutations - Plant Developmental Biology

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
Veränderungen der Chromosomen
Genetische Analyse biologischer Prozesse
Transposons bei Eukaryonten
Regulation der Genexpression
Regulation der Zellzahl - Onkogene
13. 10. 15
20. 10. 15
27. 10. 15
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01. 12. 15
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12. 01. 16
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26. 01. 16
02. 02. 16
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Gene mutations: their causes
and repair mechanisms
Genetics 10
Based on Chapter 17 (Griffiths; 10th ed.)
Summary
10
• Spontaneous and induced mutations
• Point mutations
• synonymous
• missense: conservative, nonconservative
• nonsense (STOP)
• Indels (insertion, deletion, frameshift)
• Mutagens and carcinogens
• Ames Test
• DNA Repair
• photolyases
• nucleotide excision repair
• global genomic repair
• transcription coupled nucleotideexcision repair
• etc.
• Point mutations and cancer
“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
Summary
10
• Spontaneous and induced mutations
• Point mutations
• synonymous
• missense: conservative, nonconservative
• nonsense (STOP)
• Indels (insertion, deletion, frameshift)
• Mutagens and carcinogens
• Ames Test
• DNA Repair
• photolyases
• nucleotide excision repair
• global genomic repair
• transcription coupled nucleotideexcision repair
• etc.
• Point mutations and cancer
What you need to know and understand
for the exam and for your life....
...point mutations
... indels
... types of spontaneous mutations
... examples for induced mutations
... repair mechanisms
... Ames test
Chromosome mutations
Genetics 12
Based on Chapter 16 (Griffiths; 9th ed.); Chapter 7 (10th ed.)
Euploidy and Polyploidy
Aneuploidy and Gene Balance
Changes in Chromosome Structure
Chromosomal Mutations and Disease
Types of chromosome mutations
Euploidy and Polyploidy
Chromosome constitutions
monoploid vs. haploid
male bees, wasps, and ants
are examples of monoploids
monoploids are sterile (no
meiosis possible and
propagation via mitotic
gametes)
Euploids have multiples of the basic wild type chromosome set
Aneuploids differ from the wild type by part of a chromosome set
Higher ploidy induces e.g. larger cell size
Diploid vs. tetraploid grapes
Stomata size in the
epidermis of a plant leaf
Colchicine, a (chemical) trick to induce
autopolyploidy
Chromosome pairing in an autotetraploid
Meiotic pairing in triploids
This happens for each chromosome so that the resulting gametes will
certainly have intermediate (aneuploid) chromosome numbers
-> high chance of infertility or complete sterility
Origin of the allodiploid Raphanobrassica
Origin of the varieties of Brassica oleracea
Origin of the three allopolyploid species of Brassica
Proposed origin of bread wheat by
ancestral allodiploidy
Monoploid plants from tissue culture
Polyploidization is a driving force in evolution
Aneuploidy and Gene Balance
Changes in chromosome number
monoploid vs. haploid
male bees, wasps, and ants are
examples of monploids
monoploids are sterile (no
meiosis possible and
propagate via mitotic gametes)
Euploids have multiples of the basic wild type chromosome set
Aneuploids differ from the wild type by part of a chromosome set
Meiotic nondisjunction generates aneuploid products
Characteristics of Turner syndrome (X0)
about 1:5000 of female births
Karyotype
Characteristics of Klinefelter Syndrome (XXY)
about 1:1000 of births
Karyotype
Characteristics of Down syndrome (Trisomy 21)
about 1.5:1000 of births
Karyotype
Down syndrome and maternal age
Types of chromosome mutations
Changes in Chromosome
Structure
- Deletions -
Origins of chromosomal rearrangements
Non-allelic homologous recombination (NHAR)
Gene dosage and balance
Balanced vs. unbalanced
rearrangements
Unbalanced arrangements alter
the gene ratio/dosage
Deletion loops in Drosophila
Mapping mutant alleles by pseudo-dominance
Deletion and the Cri-du-chat Syndrome
about 1:50,000 of births
Changes in Chromosome
Structure
- Duplications -
Origins of chromosomal rearrangements
Non-allelic homologous recombination (NHAR)
Map of segmental duplications in the human
genome
tandem duplications vs. insertional duplications
Duplications by ancestral polypoloidy in the
Saccharomyces genome
Changes in Chromosome
Structure
- Inversions -
Origins of chromosomal rearrangements
Non-allelic homologous recombination (NHAR)
Structural changes in the DNA by inversions
Inversion loops at meiosis
Paracentric deletions can lead to deletion products
Pericentric inversions can lead to duplicationand-deletion products
The two main chromosome-segregation
patterns in a reciprocal-translocation
heterozygote
Down Syndrome in the progeny of a
translocation heterozygote
Chromosomal mutations and
disease
Mutations can induce cancer
Somatic translocations and cancer
Somatic translocations and cancer
Fates of a million implanted zygotes
What you need to know and understand for
the exam and for your life....
...monoploidy, diploidy, etc.
... autotetraploidy vs. autotriploidy
... alloploidy (origin of wheat)
... meiotic nondysjunction and consequences
... Turner, Klinefelter, Down Syndromes
... deletion, inversion, translocation
The end