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35 Cards in this Set

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  • Back
what's the fastest way to kill endospores/sterilize?
pressure plus moist heat
what is Pasteurization used for?

what wouldn't you use it for?
to disinfect beverages

To kill endospores or thermoduric microbes
Does boiling water sterilize?

how long must you boil to achieve disinfection
no, it disinfects

30 minutes
when is dry heat (Hot Air and Incineration) used?
Common practice in microbiology lab- incineration on inoculating loops and needles using a Bunsen burner
when is a dry oven used?
Used for heat-resistant items that do not sterilize well with moist heat
Describe the use of cold and disiccation
Used to slow growth of cultures and microbes in food during processing and storage
Cold does not kill most microbes; freezing can actually preserve cultures
define dessication

define lyophilization
Desiccation: dehydration of vegetative cells when directly exposed to normal room air
Lyophilization: a combination of freezing and drying; used to preserve microorganisms and other cells in a viable state for many years
which forms of radiation are used to control microbes?
Gamma rays - most potent
X rays
Ultraviolet radiation
which is the most damaging form of radiation for us?

describe it.
ionizing radiation, i.e. gamma rays

if the radiation ejects orbital electrons from an atom causing ions to form
what are three types of ionizing radiation?

Which is most and least penetrating?
Gamma rays, most penetrating;
X rays, intermediate;
cathode rays, least penetrating
what is nonionizing radiation ultraviolet rays used for?
Usually disinfection rather than sterilization
Powerful tool for destroying fungal cells and spores, bacterial vegetative cells, protozoa, and viruses
what are some application for ionizing radiation?
Food products
Medical products
what is a physical method of removing microbes from air and liquids?
Water purification and liquids that can't withstand heat.
Removing airborne contaminants (HEPA filters
define tinctures
Tinctures: solutions dissolved in pure alcohol or water-alcohol mixtures
what are the Factors that Affect the Germicidal Activity of Chemicals?
Nature of microorganisms being treated
Nature of the material being treated
Degree of contamination
Time of exposure
Strength and chemical action of the germicide
what are some examples of halogen antimicrobials
Fluorine, bromine, chlorine, and iodine
would you use a halogen for killing endospores?
Yes, the are Microbicidal and sporicidal with longer exposure
what is an example of the halogen chlorine? what does it do?
Household bleach
Kills bacteria and endospores
Also kills fungi and viruses
what halogen would you use to apply topically to disinfect an area?
Kills bacteria and endospores
Also kills fungi and viruses
what is the action of phenol and its derivatives?
High concentrations: cellular poisons
Lower concentrations: inactivate certain critical enzyme systems
what is chlorhexidine used for?
At moderate to high concentrations, it is bactericidal for both gram-positive and gram-negative bacteria but inactive against spores
Used commonly in mouthwash
ie. Chloroseptic
what is the minimum concentration that alcohol must be to be effective?
at least 50%
would you use alcohol against a non-enveloped virus?
no, alcohols are More effective in inactivating enveloped viruses than non-enveloped viruses
what is the mechanism of action of hydrogen peroxide?
Oxygen forms hydroxyl free radicals which are highly toxic and reactive to cells
Bactericidal, virucidal, and fungicidal
could you use hydrogen peroxide against endospores?
Yes, in high concentration
what are the mechanisms of action of alcohols
mostly dissolution of membrane lipids, denaturation of proteins and dehydration
what type of detergents do you want to use to disinfect surfaces?
Cationic detergents are more effective because the positively charged end binds well with the predominantly negatively charged bacterial surface proteins
Soaps are _______microbicides but gain germicidal value when mixed with agents such as ______ or _______
chlorhexidine or iodine
define oligodynamic action
Oligodynamic action: having antimicrobial effects in exceedingly small amounts
what is the antimicrobial mechanism of action of heavy metal compound
Bind onto functional groups of proteins and inactivating them (metals are catalysts)
what are the drawbacks to using metals in microbial control?
Can be very toxic to humans
Large quantities of biological fluids and wastes neutralize their actions
Microbes can develop resistance to them
what germicide has a -CHO functional group on the terminal carbon?
–CHO functional group on the terminal carbon
examples of gaseous sterilants and disinfectants
Ethylene oxide (ETO)
Propylene oxide
Chlorine dioxide
what is the Primary source of certain drugs used in chemotherapy
what is their limitation?
Limited applications because they stain and have a narrow spectrum of activity
why are acids and alkalis limited in applications?
Limited in applications due to their corrosive, caustic, and hazardous nature