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Microbiology > Ch 7 Control of Microbial Growth > Flashcards

Ch 7 Control of Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

removal of all forms of microbial growth

A

sterilization

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2
Q

destroys Clostridium botulinum spores (criteria for food industry)

A

commercial sterilization

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3
Q

destruction of vegetative forms of bacteria

A

disinfection

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4
Q

destruction of vegetative pathogens on living tissue

A

antisepsis

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5
Q

mechanical removal from surface w alcohol swab

A

de-germing

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6
Q

washing to lower microbial count that is generally safe

A

sanitization

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7
Q

putrefaction from microbial contamination

A

sepsis

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8
Q

2 basic ways a microbe can be killed

A

alter membrane permiability (easier for things to get in, easier for components of cell to leak out)
or
damage proteins or nucleic acids inside cell (disrupts metabolism, prevents reproduction)

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9
Q

what is the thermal death point

A

lowest temp in which 10 min exposure will kill bacteria

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10
Q

what is thermal death time

A

minimum time for all microbes to die at a given temp

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11
Q

what is decimal reduction time

A

time for 90% of microbes to die at a given temp

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12
Q

what are equivalent treatments

A

same result of # of microbes killed, different temp or time

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13
Q

a higher temp means (more/less) time needed to kill

A

less

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14
Q

define moist heat sterilization

A

denatures proteins by breaking H bonds (boiling/steaming)

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15
Q

how long endospores can survive boiling

A

20 hours

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16
Q

what is the max temp of boiling water

A

212 F

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17
Q

define pastuerization

A

brief but high temp (HTST)

72 C for 15 sec or 140C for 4sec

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18
Q

which is more effective and why; dry heat sterilization or moist

A

moist; water conducts heat most efficiently than air

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19
Q

define dry heat sterilization

A

170C for 2 hr

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20
Q

HEPA filters v membrane filters

A

HEPA- filter down to ab .3um

membrane filters- down to ab .01 um

21
Q

which filter would be used to capture viruses (HEPA or membrane filters)

A

membrane

22
Q

a refrigerator is bacteria___

A

bacteriastatic

23
Q

freezing (<0C, -44F) is bacteria___ for many species

A

bacteriacidal

24
Q

how an increase of pressure affects bacteria

A

denatures proteins

25
Q

why it takes repeated cycles of pressure to eliminate endospores

A

pressure may germinate them, repeated cycles to kill

26
Q

define dessication

A

drying to kill microbes

27
Q

how osmotic pressure is used to kill microbes

A

create a hypertonic environment causing water to move out of cell (desiccating it)

28
Q

canning w sugar or salt is an example of

A

using osmotic pressure to kill microbes

29
Q

____ can tolerate high osmotic pressure

A

molds

30
Q

the shorter the wavelength the (higher/lower) the energy

A

higher

31
Q

how long are ionizing wavelengths, how they affect microbes, examples?

A

<1 nanometer, creates ions and hydroxyl radicals that can cause mutations in DNA and kill microbes;
xrays, gammarays

32
Q

how long are non-ionizing wavelengths, examples?

how they affect microbes

A

> 1 nanometer ; UV light

kills microbes by creating thymine dimers causing a bump in DNA and mutations

33
Q

what are thymine dimers

A

section of DNA w 2 thymines next to eachother, absorb UV light bonds break between adenines and a covalent bond forms between the two T’s

34
Q

wavelength bactericidal range

A

200-295

35
Q

how phenols affect microbes

A

damage PM

36
Q

what biphenols (O-phenylphenol) do

A

inhibit biosynthesis of fatty acids

37
Q

what biguanide does

example

A

disrupts PM, antiseptic

chlorhexidine

38
Q

what halogen phenols do

examples

A

disrupts enzyme function (iodine and chloride)

impairs protein synthesis, alters PM (chlorine)

39
Q

iodine + alcohol is called

A

an iodine tincture

40
Q

how alcohol affects microbes

A

denatures proteins, disrupts membranes, dissolves lipids

41
Q

why 100% alcohol is less effective than alcohol w water

A

alcohol + water helps it to penetrate lipid membrane (alcohol is non-polar)

42
Q

at what conc does alcohol begin reducing in effectivness

A

less than 50%

43
Q

how heavy metals affect microbes

A

metal ions bind to sulfur, disrupts bonds and makes proteins ineffective

44
Q

heavy metals in use for killing microbes

A

silver, copper, zinc

45
Q

what are surface acting agents and how they affect bacteria

A

soaps/detergents, emulsify/ degerm bacteria on skin

46
Q

example of surface acting agent and how it works

A

Quat compounds (benzalconium chloride)- ammonium ions replace each H w/ different organic mlcl, inhibit enzyme function, denatures protiens, disrupts PM

47
Q

most resistant to biocides

A

prions

48
Q

least resistant to biocides

A

viruses w/ lipid envelopes

49
Q

An autoclave is an example of moist or dry heat sterilization

A

Moist

Microbiology (21 decks)

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