Mutations
I. Definitions
Mutant vs Wild type
Genotype vs Phenotype
Mutation vs Allele
Nomenclature: strains, genes, and gene products
Auxotrophic mutants
Biosynthetic Catabolic
Conditional mutations
Heat Sensitive Cold Sensitive
Resistant mutations
II. Inheritance in Bacteria
Random Mutation vs Directed Change (genetic adaptation)
Darwin and Lamarck revisited
Testsing the hypothesis
Luria-Delbruck Experiment
Newcombe Experiment
Lederbergs Experiment
*All say random mutation can occur but none exclude directed change as a second mechanism
Cairnsian mutagenesis
III. Calculating the Mutation Rate
Mutation rate= #mutation events/#cell generations
Cell Generations
# of mutational events
Calculating mutation rates from bacterial cultures
Calculating mutation rates by sampling time intervals
Factors affecting the Mutation Rate
True affectors: Growth rate Media, “Target Size”, Hot Spots
Masking affectors: phenotypic lag
IV. Types of Mutations
Base pair changes
Transitions- A:T >> G:C
Tranversions- A:T >> C:G or T:A
Frameshift Insertion Deletion
Inversion Insertion Duplication
Missense vs Nonsense mutations
Characterization Questions
Is it leaky?
Whats its reversion rate?
Can you find supressors?
Intragenic supressor
Intergenic supressor
Nonsense supressors
TRNAs/partial supression/’sicko’s
V. Genetic Analysis
Selections and Screening
Positive Selection
Negative Selection
Mutagenize, Replica plating, Enrichment
Complementation
Cloning
Recombination
Mapping mutations
Supressor analysis
Gene replacements
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