Einführung in die GenetikProf. Dr. Kay Schneitz (EBio Pflanzen)
http://[email protected]: @PlantDevTUM, #genetikTUMFB: Plant Development TUM
Prof. Dr. Claus Schwechheimer (PlaSysBiol)http://wzw.tum.de/[email protected]
Einführung in die Genetik - Inhalte1 Einführung 07. 10. 14 KS
2 Struktur von Genen und Chromosomen 14. 10. 14 KS
3 Genfunktion 21. 10. 14 KS
4 Transmission der DNA während der Zellteilung 28. 10. 14 KS
5 Vererbung von Einzelgenveränderungen 04. 11. 14 KS
6 Genetische Rekombination (Eukaryonten) 11. 11. 14 KS
7 Genetische Rekombination (Bakterien/Viren) 18. 11. 14 KS
8 Rekombinante DNA-Technologie 25. 11. 14 CS
9 Kartierung/Charakterisierung ganzer Genome 02. 12. 14 CS
10 Genmutationen: Ursache und Reparatur 09. 12. 14 CS
11 Regulation der Genexpression 16. 12. 14 KS
12 Veränderungen der Chromosomen 23. 12. 14 CS
13 Genetische Analyse biologischer Prozesse 13. 01. 15 CS
14 Transposons bei Eukaryonten 20. 01. 15 CS
15 Regulation der Zellzahl - Onkogene 27. 01. 15 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
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
Summary11
• Cells respond to intrinsic and extrinsic signals by modulating transcriptional control of certain genes
• Gene activity is the result of the function of cis- and trans-acting factors
• Trans-acting proteins react to environmental signals by using built-in sensors that continually monitor cellular conditions
• Coordinated gene regulation in bacteria
• gene are often clustered into operons on the chro and transcribed together into multigenic mRNAs
• one cluster of regulatory sites per operon is sufficient to regulate expression of several genes
• Negative vs positive regulation
• repressor proteins bind to DNA at operator site thereby blocking transcription (e.g., lac operon)
• activator proteins activate transcription by binding to DNA at the promoter region (e.g., cAMP/CAP regulation of lac operon)
• Molecular anatomy of genetic switch
• regulatory proteins have DNA-binding domains (e.g., HLH) and protein-protein interaction domains (modular
• specificity of gene regulation depends on specific protein-DNA interactions mediated by the chemical interactions between aa side chains and chemical groups of DNA bases
Summary• Eukaryotic gene regulation resembles bacterial gene regulation
• trans-acting factors binding to cis-regulatory elements on the DNA
• this regulatory factors determine the level of transcription by regulating the binding of RNA pol II to the promoter of a gene
• Enhancers/UAS
• cis-regulatory elements, possibly located quite far away (>10-50kb) from promoter
• combinatorial interactions among different transcription factors
• enhanceosome: complexes of regulatory proteins that interact in cooperative and synergistic fashion --> high levels of transcription through recruitment of RNA pol II
• Gene regulation and chromatin
• eukaryotic genes are packed in chromatin
• activation/repression requires specific modifications to chromatin
• genes are mostly turned off and kept silent in part by nucleosomes and condensed chromatin
• histone code: pattern of posttranslational modifications of histone tails (acetylation, methylation, phosphorylation etc).
• histone code is an epigenetic mark involved in nucleosome positioning and chromatin condensation that can be altered by TFs
• TFs recruit for example ATP-dependent chromatin remodelers (e.g., SWI-SNF)
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
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