Chapter 5 : Environmental Influences Flashcards
what do changes in temperature impact?
membrane fluidity, nutrient transport, DNA stability, and enzyme structure and function
how would a higher optimal temperature for a microbe affect its rate of growth?
it could achieve a higher rate of growth than a microbe with a lower optimal temperature
what temperature range befits a psycrophile?
0-20 degrees Celsius
what classification of microbes are often found beneath icebergs and arctic soil due to their frigid temperatures?
psycrophiles
what are psycotrophs?
microbes that CAN grow well beneath their optimal temperature but much more slowly(ex. Listeria)
how do psycrophiles survive at such low temperatures?
their proteins are more flexible and require less heat to function; their membranes are more fluid at low temperatures due to higher fat content
what temperature range befits a mesophile?
20-40 degrees Celsius
what classification of microbes are most human pathogens?
mesophiles
what temperature range befits a thermophile?
50-65 degrees Celsius
Thermus aquaticus belongs to what classification of microbe?
thermophile
how do thermophiles survive at such high temperatures?
their enzymes do not unfold easily, allowing to maintain shape
what type of microbe can survive in extremely high temperatures of 65*C+?
hyperthermophiles
how do hyperthermophiles survive such high temperatures?
they have a fused lipid monolayer membrane with a high heat resistance
what do rapid temperature changes cause?
heat-shock response
what are barophiles?
organisms that REQUIRE elevated pressure to grow; a.k.a. piezophiles
what are barotolerant organisms?
organisms that can deal with pressures of 1-50MPa
what is the measure of the number of solute molecules in a solution, which is inversely related to the availability of water(a sub w)?
osmolarity
what is a hypertonic solution?
higher osmolarity than the cell
what is a halophilic microbe?
one that requires high salt concentration to grow
what happens when the pH difference between the inside and outside of the cell is high?
protons can leak through proteins in membrane
what are neutralophiles?
organisms that prefer an external pH of 5-8 and maintain a difference in pH of 0.5 from outside of cell as a source of energy
what are acidophiles?
organisms that prefer an external pH of 0-5 that include bacteria and archaea that live in extremely acidic environments
how does the internal pH of an acidophile compare to the pH of growth environment?
internal pH is less acidic
what are alkaliphiles?
organisms that prefer an external pH of 9-11, often found in salt lakes
what type of organism are most human pathogens in terms of pH preference?
neutralophiles
what is the process wherein all living cells, spores, and viruses on an object are destroyed?
sterilization
what is the process wherein disease-producing organisms are killed/removed from inanimate surfaces?
disinfection
what is the process wherein pathogens are removed from the surfaces of living tissues?
antisepsis
what is the process wherein microbial growth is reduced to safe levels?
sanitation
what type of rate do cells treated with antimicrobials die at?
logarithmic/exponential rate
what is the amount of time needed to kill 90% of microbial population called?
decimal reduction time(d-value)
