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Microbiology > Module 4 pt. 3 > Flashcards

Module 4 pt. 3 Flashcards

1
Q

essential ingredient of bacterial protoplasm

needed by actively metabolizing cells

A

Water

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2
Q

minimum pressure needed to be applied to a solution to prevent the flow of water across a semipermeable membrane

A

Osmotic pressure

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3
Q

organisms that can grow at relatively
high salt concentration (up to 10%)

salt-loving organisms; require relatively
high salt concentrations for growth (i.e. archea require
NaCl concentrations of 20 % or higher)

A

osmotolerant

halophiles

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4
Q

Classification of Halophiles

A

low halophiles – 1-6% NaCl

mild or moderate halophiles – 6-15% NaCl

 extreme halophiles – 15-30% NaCl

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5
Q

pressure exerted by standing water, in proportion to its depth

doubles with every 10 meter increase in
depth

A

Hydrostatic Pressure

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6
Q

bacteria that live at high pressures

Beyond 10 MPa

52 MPa and 98C

A

piezophiles (barophiles)

Psychropiezophiles

Thermopiezophiles

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7
Q

Binary Fission (5)

A
  1. Replication of chromosome
  2. Cell grow in size (double)
  3. Septum formation
  4. Completion of septum with
    formation of distinct walls
  5. Cell separation

PS. Generation - interval for the formation of two cells / time required to give rise to 2 daughter cells

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8
Q

Calculating Generation times

A

N = No2^n

  • N = final cell number
  • N0 = initial cell number
  • n = number of generations that have occurred
    during the period of exponential growth

g = t/n
* g = generation time
* t = hours or minutes of exponential growth

n=3.3 (logNt-log No)

k = 0.693/g

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9
Q

4 phases of bacterial growth curve:

A

– Lag
– Log or Exponential
– Stationary
– Decline/Death phase

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10
Q

No significant or immediate increase
in cell numbers but there may be an increase in the
size of the cell.
◼ adaptation phase

A

Lag phase

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11
Q

cells
start dividing and their number increases
exponentially
◼ organisms divide at their most rapid rate
bacteria are more susceptible to antibiotics

A

Log phase

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12
Q

cell division decreases
due to depletion of nutrients & accumulation of
toxic products; inadequate oxygen supply; pH
change
▪ growth rate tapers off

A

Stationary phase

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13
Q

Population decreases due to the death of cells
cells undergo lysis or involution (assume a variety of unusual shapes)

A

Decline (Death) Phase

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14
Q

killing or complete elimination
of all viable microorganisms

A

sterilization

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15
Q

elimination or reduction of
pathogens from inanimate objects or
surfaces

A

disinfection

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16
Q

– reduction of microbial
populations to levels considered safe by
public health standards

A

sanitization

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17
Q

prevention of infection in living
tissues using chemicals

A

antisepsis

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18
Q

one of the most useful methods of microbial control
* reliable, safe, relatively fast, inexpensive
* use to sterilize or decrease microbial number
* moist heat or dry heat

A

HEAT

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19
Q

one of the most useful methods of microbial control
* reliable, safe, relatively fast, inexpensive
* use to sterilize or decrease microbial number
* moist heat or dry heat

time required to kill all bacteria
in a particular culture at a
specified temperature

A

thermal death point

thermal death time

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20
Q
  • efficient penetrating properties
  • destroys microorganisms by irreversibly coagulating their proteins
  • boiling, pasteurization, pressurized steam
A

Moist heat

21
Q

100ºC
* destroys most bacteria
and fungi, inactivates
some viruses
* kills vegetative cells and
eukaryotic spores within
10 minutes

A

Boiling

22
Q
  • use of brief heat treatment (moderately high temperature) to
    reduce the number of spoilage organisms and kill pathogens
    (Ex. Salmonella, Mycobacterium)
A

Pasteurization

23
Q

62.8ºC for 30 minutes

72ºC, 15 seconds (flash method)

140ºC -150ºC (several seconds)

A

Low temperature holding (LTH)

high-temperature-short-time (HTST) method

ultra-high-temperature (UHT) method

24
Q
  • pressure cookers and autoclave
  • heat water in an enclosed vessel that achieves
    temperatures above 100ºC
  • 15 minutes, 15 psi, 121ºC (kills endospores and disrupts
    viruses’ nucleic acids)
A

Pressurized Steam

25
Q
  • fractional steam sterilization or intermittent sterilization
  • for materials that can be destroyed at more than 100 ºC
  • exposure to 90-100 ºC for 30 minutes for 3 consecutive days
A

Tyndallization

26
Q
  • not as efficient as wet heat (lower penetrating
    properties)
  • require longer times and higher temperatures
  • metal objects, glassware
A

Dry Heat

27
Q

oxidizes cell components to ashes

A

Incineration

28
Q

oxidizes cell components and irreversibly denature
proteins
* Petri dishes and glass pipettes
* 170ºC to 180ºC for 1 hour

A

Dry Heat Oven/Hot Air

29
Q

4 to 5 ºC
* limited to few
days because
bacteria and
molds continue
to grow at low
temperatures

A

Refrigeration

30
Q
  • 0- -95ºC
  • used to preserve food in homes and in food industries
  • slows the rate of chemical reactions in bacterial cells
A

Freezing/Deep Freezing

31
Q

remove organisms from heat-sensitive fluids
* unpasteurized beer, sterilization of sugar solutions, wine
clarification
* filtration units: remove Giardia cysts and bacteria from water
* paper-thin membrane filters (polycarbonate or cellulose
nitrate): have microscopic pores that allow liquid to pass
through while trapping small particles (vacuum or pressure)
– 0.2 µm pore removes bacteria
* depth filters: trap material within thick filtration material
(cellulose fibers or diatomaceous earth) that retain
microorganisms and let fluid pass through holes

A

Fluid Filtration

32
Q

high-efficiency particulate air (HEPA): remove from air
nearly all microorganisms with diameter greater than 0.3
µm

A

Air Filtration

33
Q

used to preserve food (absence of
water inhibits action of enzymes)
* endospores survive but do not
produce toxins

A

Drying/Desiccation

34
Q

lyophilization
* drying of material from frozen state

A

Freeze-drying

35
Q

high salt/sugar concentration create hyperosmotic
medium drawing water from microorganisms
 causes plasmolysis of bacterial cells

A

Increased Osmotic Pressure

36
Q

electromagnetic radiation: radio waves, microwaves, visible
and UV light rays, X rays, gamma rays
* ionizing and non-ionizing radiation

A

Radiation

37
Q

causes biological damage directly (destroying DNA, cell
membranes) or indirectly (produce reactive molecules, i.e.
superoxide, hydroxyl free radicals/oxidizing agents)
* kills microorganisms (0.3 to 0.4 millirads) and viruses

A

Ionizing Radiation

38
Q
  • 40 to 390 nm (200 nm)
  • damages DNA
  • effective in inactivating viruses,
    kills fewer bacteria
  • microbes in air and water,
    surfaces
  • poor penetration power
A

Ultraviolet Radiation

39
Q

disinfect and sterilize
* irreversibly react with proteins, DNA, cell membranes
* less reliable than heat; suitable for treating large
surfaces and heat-sensitive items; some are non-toxic;
can be used as preservatives (bacteriostatic)

A

Chemical Agents

40
Q
  • 60% to 80% ethyl or isopropyl alcohol
  • kill vegetative bacteria and fungi
  • coagulate enzymes and other essential proteins, damage
    lipid membranes
  • used as antiseptics for degerming or as disinfectants for
    treating instruments and surfaces
  • non-toxic, inexpensive, no residue, evaporates quickly
A

Alcohols

41
Q
  • glutaraldehyde, formaldehyde, orthophthaldehyde (OPA)
  • inactivate proteins and nucleic acids
  • 2% alkaline glutaraldehyde solution: widely used liquid
    sterilants for treating heat-sensitive medical items
  • formalin (aqueous 37% formaldehyde): kill most forms
    of microorganisms
  • toxic, irritating vapors, suspected to be carcinogenic
A

Aldehydes

42
Q
  • disrupts cell membrane, denatures proteins and
    inactivates enzymes
  • phenol, cresol, xylenol, triclosan
A

C. Phenols/Phenolics

43
Q
  • oxidation of cell constituents
  • iodine, chlorine
A

D. Halogens

44
Q
  • denatures enzymes and essential proteins
  • i.e. silver nitrate (prevents ophthalmic gonorrhoeae); copper
    sulfate (algicide); silver sulfadiazine (used on burns);
    merthiolate (disinfects skin mucous membranes)
A

E. Heavy Metals

45
Q
  • denatures proteins
  • i.e. ethylene oxide, ozone, chlorine dioxide
  • for heat-sensitive items (catheters, plastic Petri dishes)
A

F. Sterilizing Gases

46
Q
  • soaps and acid-anionic detergents: mechanical removal
    of microorganisms
  • cationic detergents: disrupt cell membrane and denature
    proteins
A

G. Surface Active Agents or
Surfactants

47
Q
  • inhibit microbial metabolism
  • sorbic acid, benzoic acid, calcium propoionate
  • widely used in foods/cosmetics
A

H. Organic Acids

48
Q
  • oxidation of cell components
  • i.e. hydrogen peroxide
A

I. Other Oxidizing Agents

49
Q
  • oxidation of cell components
  • i.e. hydrogen peroxide
A

I. Other Oxidizing Agents

Microbiology (25 decks)

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