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Molecular Cell Biology of the Yeast Saccharomyces cerevisiae. Lecture I: Biology, Genetics, Genomics and Proteomics Zhang Yi, National Institute of Biological Sciences, 20080511. Cellular Anatomy. Life History. Cell Cycle. Mitosis V.S Meiosis. α. α. a. a. Sexual Reproduction: Mating.
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Molecular Cell Biology of the Yeast Saccharomyces cerevisiae Lecture I: Biology, Genetics, Genomics and Proteomics Zhang Yi, National Institute of Biological Sciences, 20080511
Mitosis V.S Meiosis α α a a
Mating Type Switch x HO knockout renders haploid stable in propagation
Growth Conditions • Liquid: 30c O/N • Doubling: 90min in YPD and 120min in SC • Solid phase: 30c, 2-3 days • Medium: YPD/YPG/SC/SD (see ref) • Selection: nutrient deficiency, colour, reporter gene expression, temperature sensitivity, chemical resistance, et ceterus
Genetic Nomenclature Sherman 2002
Routinely Used Genetic Markers • HIS3: histidine synthesis, positive selection in his- SC medium, epistatic selection together with 3-AT • LEU2: leucine synthesis, positive selection in leu- SC medium. • TRP1: tryptophan synthesis, positive selection in trp- SC medium, negative selection on FAA containing medium • URA3: uracil synthesis, positive selection in ura- SC medium, negative selection in 5-FOA containing medium • ADE2: adenine synthesis, positive selection in ade- SC medium, ade2 colony red coloured in low ade, complete medium • CAN1: histidine and arginine transporter, negative selection in canavanine containing medium • LacZ: transgenic reporter, colony blue coloured in X-Gal containing medium upon expression
Vector Components Selectible Markers Transcription Terminator Multiple Cloning Site (MCS) Centromere sequence or Plasmid replication origin Transcription Promoter
Classical Mutagenesis Mutagen (usually toxic drug…)
PCR-based Gene Engineering 40-50bp homology arm each side
Alleles and Phenotypes • Wild-type allele: phenotypically normal function (maybe different DNA sequence) • Hypermorph: increased function • Hypomorph: lowered function • Null: no function whatsoever, completely dead • Neomorph: novel function gained (…) • Conditional: interacting with certain environmental conditions, e.g. can grow at 23c but not at 37c, can only grow in histidine containing medium, etc • Dominant: Suppresses allelic phenotype • Recessive: Suppressed by allelic phenotype
Critical Thinking Concepts • Gain-of-Function: a mutation such that confers novel, or enhanced function of a gene • Provides sufficiency • Loss-of-Function: a mutation such that lowered or abolished the function of a gene • Provides necessity • Epistasis: interaction between genes
Complementation YFG ts (recessive) Vector with Genomic Fragment Containing YFG+ Dead at 37c Live at 37c
Non-complementation (Allelic) YFG ts Hybrid Mating with Lines having Known Mutations that have similar phenotype Known mutant Dead at 37c Dead at 37c
Non-complementation (dominant negative) YFG ts (DN) Vector with Genomic Fragment Containing YFG+ Dead at 37c
Non-complement(2um deficiency) Cir0, mat(alpha) lines with FRT inserted on different chromosomes FRT CEN 2um (FLP+) FRT CEN x mutant 2um (FLP+) CEN x mutant CEN Cir+, mat(a) mutant line
Non-complement(2um deficiency) x mutant CEN FRT CEN FLP x 2um (FLP+) mutant CEN FRT CEN x mutant CEN FLP-mediated loss of FRT-inserted chromosome IF the mutant loci is on this FRT-inserted chromosome, it will reveal phenotype (haploid of recessive mutant)
Genetic Interaction • Upstream: mutantA + mutantB = phenotype B • Downstream: mutantA + mutantB = phenotype A • Enhancer: mutantA + mutantB = enhanced phenotype B • Suppressor: mutantA + mutantB = suppressed phenotype B
Genetic Interaction Hedgehog Patched Smoothened Patched; Hedgehog Patched; Smoothened Hedgehog Wild type Patched Smoothened Smoothened; Hedgehog Drosophila Larvae Pattern (simplified)
Genetic Interaction Luck (…)