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Microbiology > Ex. 2-8; 2-9; 2-12 > Flashcards

Ex. 2-8; 2-9; 2-12 Flashcards

1
Q

cardinal temperature

A

the minimum, maximum, and optimum temperature any single species can survive within.

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2
Q

psychorophiles

A

organisms that will only grow below 20 degrees Celsius with little or no fluctuation.

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3
Q

psychrotrophs

A

organisms adapted to cold habitats that fluctuate from about 0 to above 30 degrees Celsius.

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4
Q

mesophiles

A

organisms adapted to temperatures between 15 and 45 degrees Celsius.

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5
Q

thermophiles

A

organisms adapted to temperatures above 40 degrees Celsius.

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6
Q

obligate thermophiles

A

thermophiles that will not grow at temperatures below 40 degrees Celsius.

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7
Q

facultative thermophiles

A

thermophiles that will grow below 40 degrees Celsius

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8
Q

extreme thermophiles

A

thermophiles that can survive temperatures in the 65 and 110 degree Celsius range (up to 122 degrees Celsius for Methanopyrus)

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9
Q

What temperature do extreme thermophiles grow best at?

A

above 80 degrees Celsius

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10
Q

What are most bacterial residents in the human body, as well as numerous human pathogens?

A

mesophiles

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11
Q

What environmental factors affect the growth rate of microbes?

A
  1. temperature
  2. pH
  3. osmotic pressure
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12
Q

What does pH stand for?

A

pondus hydrogenii

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13
Q

What is Sorensen’s formula for the calculation of pH is expressed as:

A

pH = -log[H+]

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14
Q

How many moles of hydrogen ions per liter does water have? What is the pH of water?

A

10 -7 moles

pH of 7

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15
Q

acidophiles

A

organisms adapted to grow well in environments below about pH 5.5

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16
Q

neutrophiles

A

organisms that prefer pH levels between 5.5 and 8.5

17
Q

alkaliphiles

A

organisms that live above pH 8.5

18
Q

Under natural circumstances, the majority of bacteria maintain what kind of internal environment?

A

near-neutral

19
Q

What allows the majority of bacteria to maintain their internal environment regardless of their habitat?

A

they have cytoplasmic buffers

20
Q

What can changes to pH outside an organism’s range do?

A

it may destroy necessary membrane potential (used in ATP production) and damage vital enzymes beyond repair. This denaturing my be minor but is usually lethal to the cell.

21
Q

What is the ideal pH for Alcaligenes faecalis?

A

Ideal pH 7-11

22
Q

What is the ideal pH for Lactococcus lactis?

A

Ideal pH in the range of 6.3 to 6.9, but the lower limit for growth is within the range of 4.0 to 5.0

23
Q

What is the ideal pH for Escherichia coli?

A

Ideal pH range 5-7 optimum pH is 6

24
Q

What does UV stand for?

A

ultraviolet

25
Q

Ultraviolet radiation is a type of what?

A

electromagnetic energy

26
Q

How does UV travel?

27
Q

How is UV distinguishable from all other electromagnetic energy?

A

by its wavelength

28
Q

What is a wavelength and what is its typical unit of measurement?

A

the distance between adjacent wave crests

measured in nanometers

29
Q

What are the three groups of UV light and their measurements?

A
  1. UV-A: the longest wavelengths, ranging from 315 to 400 nm
  2. UV-B: wavelengths between 280 and 315 nm
  3. UV-C: the most detrimental to bacterial, wavelengths ranging from 100 to 280 nm
30
Q

What happens if a bacteria is exposed to UV-C for more than a few minutes?

A

usually results in irreparable DNA damage and death of the organism.

31
Q

What is the germicidal effect of UV-C related to?

A
  • time of exposure
  • lamp intensity
  • distance to the target
  • “line of sight”
32
Q

What does “line of sight” refer to?

A

UV-C does not penetrate well, bend around corners, or trickle into crevices so it must have direct access to the surface being decontaminated.

33
Q

What are thymine dimers?

A

DNA lesions induced by UV rays

34
Q

As you decrease the wavelength of light, what happens to the energy?

A

it increases

35
Q

What two microbes did we use to test the effect of UV radiation? Which tolerates it better and why?

A
  1. Bacillus subtilis tolerates UV radiation better because it has endospores.
  2. Escherichia coli
36
Q

What temperature does Escherichia coli grow best at?

A

optimum temperature for its growth is around 37 degrees Celsius.

37
Q

What temperature and pH does Serratia marcescens grow best at?

A

Optimally, Serratia marcescens grows at 37°C, but it can grow in temperatures that range from 5–40°C. They grow in pH levels that range from 5 to 9 [14].

38
Q

What temperature does Pseudomonas aeruginosa grow best at?

A

Its optimum temperature for growth is 37°C, and it is able to grow at temperatures as high as 42°C

39
Q

What temperature does Staphylococcus epidermidis grow at?

A

Since it is a pathogen of the human skin, S. epidermidis grows best at 37°C (mesophilic), the optimal temperature for the human body.

Microbiology (21 decks)

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