Lecture 14 – Flashcards

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question
generation time
answer
The time it takes for a cell to double (in both mass and
number)
question

review all the math in lecture 14 (bring calc to exam)

be able to calculate generation times and growth rate constants

answer
yahhh bitch, yahhh!
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growth rate constant
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k = log N - logN0
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batch culture
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A culture growing in an enclosed vessel such
as a tube or flask where exponential growth
cannot continue indefinitely
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inoculum
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a substance (a virus or toxin or immune serum) that is introduced into the body to produce or increase immunity to a particular disease
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Liebig’s law of the minimum
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states that growth is controlled not by the total of resources available, but by the scarcest resource (limiting factor).
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dilution rate
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  • can be the same as growth rate in a continuous culture
  • can be controlled by adjusting the
    flow rate of fresh medium containing limiting amounts of growth factor
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washout
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the point where growth can not balance dilution because dilution rate is too large (growth rate doesn't equal dilution rate)
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VBNC

;

answer

Viable, but not culturable

  • During stationary-death phases, some microorganisms (Gram negatives in particular) will gradually lose their ability to recover and reproduce when returned to standard nutrient conditions
  • These cells have metabolic activity and are structurally VBNC intact
  • May be a survival mechanism ; a quiescent state analogous to the endospore (but not heat stable)
question
how can growth factor bioassays be used to measure concentrations of certain vitamins
answer
  • by measuring the growth rate or growth yield of a fastidious organism in a defined medium containing the food sample as the sole vitamin source and all other essential nutrients provided in excess.
  • Microbe can;t make the vitamin so it must be present in the culture medium for the organism to grow. The growth response is proportional to the vitamin concentration in the medium (sole source from the food sample).
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