MICB 201 Lecture Notes - Lecture 12: Microbiological Culture, Doubling Time, Graph Paper
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6. 1 (cid:862)prokaryotes exhibit enormous diversity with respect to the environmental conditions under which they thrive. Indeed, many types of prokaryotes live under environmental regimes considered quite harsh from the standpoint of human biology. At the extremes of livability on the planet, one finds archaea and bacteria. (cid:863) (cid:894)p. 161 te(cid:454)t(cid:895: has implications for the search for extraterrestrial life and the contamination of other planets with terrestrial life by humans. To evaluate how an environmental variable affects growth, one way is to measure growth rate. Unicellular organisms: organism = 1 cell (cid:862)growth(cid:863) alwa(cid:455)s (cid:373)ea(cid:374)s population growth: u(cid:374)icellular orga(cid:374)is(cid:373)s do(cid:374)"t get co(cid:374)ti(cid:374)uall(cid:455) bigger. Population growth in laboratory: batch culture: growth in a semi-closed system (fixed volume of nutrient solution, only gas exchange with environment) Lag phase organisms express genes for new proteins required to reproduce under new environment conditions (metabolic adjustment) Exponential growth phase organisms divide with a constant doubling time (population growth)
