BIOL 222 Lecture 31: Mutations II
22 Nov 2016
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Intragenic = mutant mutations: only one out of enzyme or substrate is mutated, blocks off a pathway, prematurely terminates translation through nonsense codon. Intergenic = supressor mutations: interaction suppressor. Both enzyme and substrate are mutated: bypass suppressor. When one pathway is blocked off, another pathway worked: nonsense suppressor. Two theories about mutation: random mutation - mutation occurs prior to selection. Ex. bacteria all carry x mutation, but exist along cells that don"t carry x. Then, bacteriophage comes in, and only cells with x mutation survive: so the mutations existed before selection, physiological adaption - mutation occurs in response to selection. Ex. bacteria have no mutations, but suddenly are exposed to phage, which causes mutations to start occurring within the population. Luria - delbr ck fluctuation test: tonr gene in bacteria. Tons = sensitive to phage: coated plate with t1 bacteriophage. Added e. coli and observed that there was surviving colonies.
