Chapter 5 : Environmental Influences

Question 1

what do changes in temperature impact?

Answer 1

membrane fluidity, nutrient transport, DNA stability, and enzyme structure and function

Question 2

how would a higher optimal temperature for a microbe affect its rate of growth?

Answer 2

it could achieve a higher rate of growth than a microbe with a lower optimal temperature

Question 3

what temperature range befits a psycrophile?

Answer 3

0-20 degrees Celsius

Question 4

what classification of microbes are often found beneath icebergs and arctic soil due to their frigid temperatures?

Answer 4

psycrophiles

Question 5

what are psycotrophs?

Answer 5

microbes that CAN grow well beneath their optimal temperature but much more slowly(ex. Listeria)

Question 6

how do psycrophiles survive at such low temperatures?

Answer 6

their proteins are more flexible and require less heat to function; their membranes are more fluid at low temperatures due to higher fat content

Question 7

what temperature range befits a mesophile?

Answer 7

20-40 degrees Celsius

Question 8

what classification of microbes are most human pathogens?

Answer 8

mesophiles

Question 9

what temperature range befits a thermophile?

Answer 9

50-65 degrees Celsius

Question 10

Thermus aquaticus belongs to what classification of microbe?

Answer 10

thermophile

Question 11

how do thermophiles survive at such high temperatures?

Answer 11

their enzymes do not unfold easily, allowing to maintain shape

Question 12

what type of microbe can survive in extremely high temperatures of 65*C+?

Answer 12

hyperthermophiles

Question 13

how do hyperthermophiles survive such high temperatures?

Answer 13

they have a fused lipid monolayer membrane with a high heat resistance

Question 14

what do rapid temperature changes cause?

Answer 14

heat-shock response

Question 15

what are barophiles?

Answer 15

organisms that REQUIRE elevated pressure to grow; a.k.a. piezophiles

Question 16

what are barotolerant organisms?

Answer 16

organisms that can deal with pressures of 1-50MPa

Question 17

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)?

Answer 17

osmolarity

Question 18

what is a hypertonic solution?

Answer 18

higher osmolarity than the cell

Question 19

what is a halophilic microbe?

Answer 19

one that requires high salt concentration to grow

Question 20

what happens when the pH difference between the inside and outside of the cell is high?

Answer 20

protons can leak through proteins in membrane

Question 21

what are neutralophiles?

Answer 21

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

Question 22

what are acidophiles?

Answer 22

organisms that prefer an external pH of 0-5 that include bacteria and archaea that live in extremely acidic environments

Question 23

how does the internal pH of an acidophile compare to the pH of growth environment?

Answer 23

internal pH is less acidic

Question 24

what are alkaliphiles?

Answer 24

organisms that prefer an external pH of 9-11, often found in salt lakes

Question 25

what type of organism are most human pathogens in terms of pH preference?

Answer 25

neutralophiles

Question 26

what is the process wherein all living cells, spores, and viruses on an object are destroyed?

Answer 26

sterilization

Question 27

what is the process wherein disease-producing organisms are killed/removed from inanimate surfaces?

Answer 27

disinfection

Question 28

what is the process wherein pathogens are removed from the surfaces of living tissues?

Answer 28

antisepsis

Question 29

what is the process wherein microbial growth is reduced to safe levels?

Answer 29

sanitation

Question 30

what type of rate do cells treated with antimicrobials die at?

Answer 30

logarithmic/exponential rate

Question 31

what is the amount of time needed to kill 90% of microbial population called?

Answer 31

decimal reduction time(d-value)