(英文)细胞生物学lecture22-细胞循环

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Budding and fission yeast : organisms to study the genetics of cell cycle regulation in eukaryotes
nb - not to scale !
Saccharomyces cerevisae Brewer's / Baker's yeast division by budding
Schizosaccharomyces pombe Brewer's yeast (pombe = beer in Swahili !) division by fission
Key features of yeast that make them an attractive model system to study eukaryotic cell cycle • Eukaryote. • Reproduce almost as fast as bacteria. • Genome size c. 1% of mammals. • Are amenable to rapid genetic manipulation - replace, delete, alter genes. • Proliferate in haploid state, which makes it VERY easy to isolate mutants.
Recommended Reading: MBOC 5e, pages 1053 - 1060
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An organism to study the genetics of cell cycle regulation in eukaryotes : what are desirable criteria ?
Schizosaccharomyces pombe Brewer's yeast (pombe = beer in Swahili !) division by fission
Suited for analysis of G1->S transition
Suited fBaidu Nhomakorabear analysis of G2->M transition
Wild type
Dominant
Recessive
Wild type
Mutant
Mutant
• Hemizygous, mutant organism displays mutant phenotype. • This precludes crossing (breed) organism to identify mutants. • (To discriminate between dominant and recessive alleles, you have to examine organism in diploid stage of life-cycle - i.e. in the case of yeast, you have to mate them).
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Organisms whose life cycle includes a haploid phase simplify identification of genes required for a biological process
Cell with mutation is (usually) viable due to presence of wildtype (back-up) allele
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Budding and fission yeast : organisms to study the genetics of cell cycle regulation in eukaryotes
nb - not to scale !
Saccharomyces cerevisae Brewer's / Baker's yeast division by budding
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Organisms whose life cycle includes a haploid phase simplify identification of genes required for a biological process
• Heterozygous, recessive mutant organism rarely shows mutant phenotype. • Organism must be made homozygous for the mutation to observe the mutant phenotype. HAPLOID GENOTYPE HAPLOID PHENOTYPE
Lecture 22 – Cell Cycle III - Experimental analysis using Genetics
Discovery of cyclin dependent kinases (Cdks)
Supervisors of the cell cycle control system - association of two classes of proteins, cyclins and cyclin-dependent kinases (Cdk), trigger key events during the cell cycle.
• • • • • • Eukaryote (not bacteria !). Rapid life cycle (not Xenopus !). Cell cycle similar to that found in 'higher' eukaryotes. Ease of growth / maintenance (no elephants !). Easy to mutagenize. Suitable for biochemical analysis - easily propagated in large quantities.