Biology 1002B Lecture Notes - Lecture 12: Experimental Evolution, Gene Duplication, Citric Acid
29 Aug 2016
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Class 24: characteristics of model systems that can be used for experimental evolution. Fast reproductive cycle, generation time: measuring relative fitness in e. coli. Relative fitness (w) = gr of evolved strain/ gr of ancestral strain. Higher to 1, higher relative fitness: design of lenski"s long term evolutionary experiment (lee) with e. coli. Everyday, transfer 100 microliters of e. coli to new medium (12 groups in total), freeze a sample every few generations. Can compare evolved strains to ancestral strains: value of cryopreservation to lee. Can freeze ancestral cultures of e. coli for comparison with evolved strains over time: where citrate enters metabolism. Citrate is an intermediate molecule used in metabolic systems (kreb"s cycle: role of glucose limitation in lee experiment. Glucose amount of limited to limit the population size of the e. coli culture. Thaw ancestral cultures at various times, if some give rise to cit+ phenotype, then it is a contingent mutation.
