Post on 03-Oct-2020
Einführung in die GenetikProf. Dr. Kay Schneitz (EBio Pflanzen)
http://plantdev.wzw.tum.dekay.schneitz@tum.deTwitter: @PlantDevTUM, #genetikTUMFB: Plant Development TUM
Prof. Dr. Claus Schwechheimer (PlaSysBiol)http://wzw.tum.de/sysbiolclaus.schwechheimer@wzw.tum.de
Einführung in die Genetik - Inhalte1 Einführung 13. 10. 15 KS2 Struktur von Genen und Chromosomen 20. 10. 15 KS3 Genfunktion 27. 10. 15 KS4 Transmission der DNA während der Zellteilung 03. 11. 15 KS5 Vererbung von Einzelgenveränderungen 10. 11. 15 KS6 Genetische Rekombination (Eukaryonten) 17. 11. 15 KS7 Genetische Rekombination (Bakterien/Viren) 24. 11. 15 KS8 Rekombinante DNA-Technologie 01. 12. 15 CS9 Kartierung/Charakterisierung ganzer Genome 08. 12. 15 CS
10 Genmutationen: Ursache und Reparatur 15. 12. 15 CS11 Veränderungen der Chromosomen 22. 12. 15 CS12 Genetische Analyse biologischer Prozesse 12. 01. 16 CS13 Transposons bei Eukaryonten 19. 01. 16 CS14 Regulation der Genexpression 26. 01. 16 KS15 Regulation der Zellzahl - Onkogene 02. 02. 16 CS
Gene mutations: their causes and repair mechanisms
Genetics 10
Based on Chapter 17 (Griffiths; 10th ed.)
Summary10
• 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 nucleotide-excision 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
deoxyribophosphodiesterase
apurinic/apyrimidinic endonuclease
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
Summary10
• 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 nucleotide-excision 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 mutationsGenetics 12
Based on Chapter 16 (Griffiths; 9th ed.); Chapter 7 (10th ed.)
Euploidy and Polyploidy
Aneuploidy and Gene Balance
Chromosomal Mutations and Disease
Changes in Chromosome Structure
Types of chromosome mutations
Euploidy and Polyploidy
Chromosome constitutions
Euploids have multiples of the basic wild type chromosome setAneuploids differ from the wild type by part of a chromosome set
monoploid vs. haploid
male bees, wasps, and ants are examples of monoploids
monoploids are sterile (no m e i o s i s p o s s i b l e a n d propagation via mitotic gametes)
Higher ploidy induces e.g. larger cell size
Diploid vs. tetraploid grapes
Stomata size in theepidermis 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 byancestral allodiploidy
Monoploid plants from tissue culture
Polyploidization is a driving force in evolution
Aneuploidy and Gene Balance
Changes in chromosome number
Euploids have multiples of the basic wild type chromosome setAneuploids differ from the wild type by part of a chromosome set
monoploid vs. haploid
male bees, wasps, and ants are examples of monploids
monoploids are sterile (no meiosis possible and propagate via mitotic gametes)
Meiotic nondisjunction generates aneuploid products
Characteristics of Turner syndrome (X0)
Karyotypeabout 1:5000 of female births
Characteristics of Klinefelter Syndrome (XXY)
Karyotypeabout 1:1000 of births
Characteristics of Down syndrome (Trisomy 21)
Karyotypeabout 1.5:1000 of births
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 theSaccharomyces 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 duplication-and-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