Luria &
Delbruck Thought Experiment #2 : Mutation
As before, four
cultures are started from one cell each, and undergo 15 divisions
in four generations to produce 16 cells each, and 64 total. In the
final generation, among 64 cells total, 10 cells
are observed to be resistant (red). If resistance arose by
spontaneous mutations prior to exposure to
bacteriophage in the last generation, then the individual
cultures will have variable numbers of resistant cells, depending
on whether the mutations occurred early (as in Culture
3) or late (as in Culture 1) or not at all
(Cultures 2 & 4). The variance among cultures will vary
("fluctuate") strongly,
and will increase further as the number of generations increases.