MIMM 211 Lecture Notes - Lecture 9: Exponential Growth, Doubling Time, Geometric Progression
29 Aug 2016
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Document Summary
Population growth: exponential growth, synchronous growth, asynchronous growth, generation time. Mathematical expression of population growth: the growth curve. During active growth, populations of unicellular microorganisms increase exponentially by geometric progression (2^n) When timing of cell division is random, asynchronous cultures result and produce at a smooth exponential growth plot. When cells divide synchronously, a step wise growth plot can be seen. Accumulation of toxic metabolic compounds doubling time increases: generation time determination is easy (look at the slope ) Growth curve is easy to look at. Cells stop growing and die however, not all cells die. Reasons for a longer lag phase: inoculum taken from an old culture, inoculum taken from a rich medium and added to a poorer one. No lag occurs when growing cells are transferred from a poor to a richer medium: inoculum taken from a chemically different medium, inoculum taken from refrigerated cells, cells inoculated into a cold medium.
