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184 Cards in this Set
- Front
- Back
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Microbial contamination
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sepsis
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absence of significant contamination
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asepsis
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prevents contamination of culture, personnel, and the environment
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antiseptic technique
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Eliminating ALL microbial life EVEN virus
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sterilization
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Is commercial sterilization real sterilization
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no
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Commercial sterilization
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used for processing canned food
kills everything except thermophilic spores |
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Can thermophilic spores germinate at ambient temperature
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no
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Can thermophilic spores survive commercial sterilization
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yes
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What should you store canned foods at
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under 40 degrees C
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eliminating vegetative pathogens
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disinfection
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What is the purpose of disinfection
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to reduce the risk of infection or spoilage
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What is antisepsis
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eliminating vegetative pathogens from living tissues
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What is the difference between disinfection and antisepsis
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different uses: one is on surfaces; one on tissues
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What is disinfection plus cleaning
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sanitization
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What is the purpose of sanitization
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eliminate pathogens, organic debris, dirt
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What is microbicide?
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kills mos
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What is germicide
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kills germs
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What do microbicide/germicide do?
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kill microbes
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What is inhibiting but not killing microbes
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microbistasis
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What is microbial death rate
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log rate death: drop by one log
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What does the effectiveness of antimicrobial treatment depend on?
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number of microbes, exposture time, susceptibility of the microbe, environmental conditions, and concentration/dose of the agent
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What is very resistant to drying and chemical treatments
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mycobacterium/ waxy layer
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What is very resistant to all treatments
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spores/ multiple layers
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Why are G- more resistant
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outer membrane with selective permeability
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What are some environmental conditions that affect antimicrobial treatment
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temperature, pH, moisture, organic substances
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What does a higher temp generally do
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speed up reaction
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What are some organic substances that protect mos
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sugar, fat, polysaccharide
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What does chlorine work best in
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acidic pH
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In acidic env't, mos can be killed...
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with a lower temperature
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What is the only exception to the fact that antimicrobial effect increases with the concentration or dosage
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alcohol
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What must alcohol be used with
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water
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What do microbial control agents do?
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alternation of membrane permeability, damage to proteins, damage to nucleic acids
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What is the time to kill all cells in a culture with heat
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thermal death time
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What is the lowest temperature at which all cells in a culture are killed in 10 minutes
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thermal death point
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What is the minutes it takes to kill 90% of a population at a given temperature
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decimal reduction time
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What is the commonly used time?
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decimal reduction time
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What does a longer TDT (thermal death time) mean?
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harder and more resistant
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What is the most commonly used method?
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heat?
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What does moist heat do?
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denature proteins
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What is steam under pressure
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autoclave
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What are some examples of moist heat
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boiling, autoclave
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in order to heat water above 100 degrees C at sea level, what must you do?
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use pressure
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The higher the pressure...
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the higher the boiling point
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What are some things you should not autoclave?
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heat sensitive, flour, milk powder, vitamins, antibiotics, water insoluble substnaces
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What will a larger volume mean for autoclaving?
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longer to penetrate
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What is the protein that causes mad cow disease
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prion
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What degrees is boiling
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100 degrees
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Can you use boiling for sterilization
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no, cannot kill endospores
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Does boiling kill vegetative cells
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yes
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Does boiling kill viruses
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some
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Does boiling kill endospores
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no
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Does boiling kill mold spores
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probably
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What is a mild heat treatment used to reduce spoilage organisms and pathogens
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pasteurization
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What are some things that are pasteurized
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milk, OJ, cheese, sauerkraut
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What are the types of pasteurization
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low temp holding, high temp short time, ultra high temp
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what is low temp holding?
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use a low temp about 63 degrees celsius for 30 minutes
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What is high temp short time
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72 degrees C for 15 seconds
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What is ultra high temp?
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140 degrees celsius for less than one second
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What can destroy milk over time
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enzymes
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What organisms survive pasteurization
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thermoduric
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What is special about ultra high temperature
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can be shelf stored because it kills spoilage pathogens
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How does dry heat kill
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oxidation
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Does dry heat penetrate
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no
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What requires a higher temp and longer exposure due to slow penetration
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dry heat
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What are some examples of dry heat?
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flaming, incineration, hot air sterilization
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What is the oven equivalent to dry heat
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hot air oven 170 degrees C for 2 hours
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What is the autoclave equivalent of dry heat
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121 degrees C for 15 minutes
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low temperature
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cannot control microbial growth but cannot be used to destroy mos and preserves microbial culture
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Most what wont grow during refrigeration
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mesophiles
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What grow slowly in refrigeration
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psychrophiles
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What occurs at a lower temp
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slower growth rate
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What occurs if the temp is really low
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wont grow
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Can mos grow w/o water
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no
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Why can cells not grow if frozen
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if the water in the cell is frozen, it won't have water for growth
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What is slow freezing
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-20 degrees C for several hours
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What is fast freezing
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-70 degrees C within 20 minutes
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What is freeze drying
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freezes instantly and then dries
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What is used to preserve stuff?
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fast freezing
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What is freezing?
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below 0 degrees: not pure H20
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What is freezing material rapidly first and then dry under the vacuum
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freeze drying
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What is freeze drying?
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gently used to preserve bacterial cultures
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Is low temperature used to kill mos?
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no
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What type of mos will grow at refrigeration temperatures?
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psychrotrophs
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Will mos grow at freezing temperatures?
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no
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Which of the following types of freezing is more harmful to microbes?
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slow freezing
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What is removing water to stop microbial growth?
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drying
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What does dessication do?
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prevents metabolism
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What is drying used for?
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food preservation
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What survives drying?
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most mos but not all: spores survive well
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What causes plasmolysis?
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high osmotic pressure
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What is plasmolysis?
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cell shriking
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Why do we use salt and sugar to preserve food?
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create a high osmotic pressure (hypertonic env't) in which mos lose H20 and can't grow
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What grows in a high salty env't?
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halophiles
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What does radiation do?
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damage DNA
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What are types of ionizing radiation
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x rays, gamma rays, electron beams
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What is non ionizing radiation?
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UV
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How do microwaves kills mos?
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by heat, not by radiation
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How does a microwave generate heat?
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by friction
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What does UV radiation do?
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make T-T dimers
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What can become sterile without heat
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gamma rays
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What is the only type of radiation that kills microbes
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ionizing
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What does ionizing radiation do
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break DNA, irradiated H2O generates free radicals to damage cells
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Can you use ion radiation to cause sterilization?
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yes
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What is the most effect wavelength to kill mos?
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260 nm
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What are bacteriocidal wavelengths?
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200-280 nm
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What is stronger bacteriocidal?
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shorter wavelength
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What is only effective on the surface
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UV light
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What is UV light
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136-400 nm
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What is the most effective wavelength
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260 nm
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What is UV absorbed by
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cellular DNA and form thymine dimers that distort DNA strands
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What is the major disadvantage of using UV?
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poor penetration power
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What does filtration do
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removes microbes (particles) from liquid or air
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What stays on the filter in membrane filtration?
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anything larger than spores
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What is an example of membrane filtration?
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hood
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What should you use a hood for?
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mycobacterium/ TB
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What could pass through the pore size of 0.22 micrometers?
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small viruses, pliable bacteria and prions
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What could pass through the pore size of 0.45 micrometers?
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viruses, small bacteria and prions
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What does HEPA stand for?
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high efficiency particulate air
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What does high pressure do?
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denatures proteins and damages cell structures
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What can be pasteurized
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OJ
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What is the advantage of high pressure
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doesn't use heat, heat can destroy flavor
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What are factors that influence chemical controls?
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concentration of disinfectant, organic matter (protect mos), pH, temperature, time
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WHat does an acidic pH do?
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may decrease resistance or usually an increase in temperature, you get a better result
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What are the only chemicals that can kill endospores?
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chemosterilants
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What are some chemosterilants?
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ethylene oxide, glutaraldehyde, heated hydrogen peroxide, peracetic acid
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What can treat surgical instruments?
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glutaraldehyde
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What is the BP of ethylene oxide?
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10.2 degrees C- toxic
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What is the disadvantage to using ozone?
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no toxic residuals because it must travel in pipes and recontaminate
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What does peracetic acid do?
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kills endospores within 30 minutes, kills vegetative cells within 5 minutes
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How is peracetic used?
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on food processing and medical equipment
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What are the advantages of using peracetic acid?
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no toxic residuals, not affected by organic matters
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What is the application of hydrogen peroxide?
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aseptic food packaging materials are sterilized with hot solution of hydrogen peroxide
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What is hydrogen peroxide?
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35% H2O2 and 40-80 degrees C
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What is the advantage of hydrogen peroxide
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no toxic residual, vaporized H2O2, high penetration
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What is hydrogen peroxide used at home for
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generate O2 bubbles to lift dirt
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What does hydrogen peroxide break down into
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water and O2
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What is a phenol coefficient of 1
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same as phenol
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What is a phenol coefficient over 1
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better than phenol
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What a phenol coefficient below 1
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not as good as phenol
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What is phenol
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toxic and irritating
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What are derivatives of phenol that are less irritating
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phenolics
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What is used nowadays?
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phenolics
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What is the very 1st disinfectant ever used?
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phenol
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What will most likely not kill endospores
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phenol/phenolics
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PAGE 280
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TABLE 9.5
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What is effective against all bacteria, many endospores, fungi and viruses?
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iodine
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What is iodine in alcohol solution
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tincture of iodine
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What is iodine plus an organic carrier
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iodophore
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What slowly releases iodine and is less irritating but doesn't stain?
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iodophore
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What is not very pleasant; burns
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tincture of iodines
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What are some oxidizing agents that inactive enzymes
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halogens, iodine, chlorine
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What is used to treat water effective concentration of 0.5-1.0 ppm
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chlorine
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What is HOCl
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hypochlorous acid
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How does pH influence the effectiveness of chlorine
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in an acidic env't a lot of hypochlorous acid is made
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What is bleach?
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sodium hypochloride (NaOCL)
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What is an active antimicrobial ingredient?
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hypochlorous acid
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What inactivates proteins by cross linking with functional groups?
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aldehydes
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How can aldehyde kill spores
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probably for a high concentration for a long time
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What is used for disinfection of medical equipment?
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glutaraldehyde
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What is used for fumigation?
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formaldehyde gas
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What is used to disinfect a whole room?
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formaldehyde
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What is formalin?
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37% aqueous soluntion of formaldehyde that is used to preserve corpse, tissue, inactive viruses to prepare vaccines
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What denatures proteins and dissolves lipids and can kill vegetative cells but not endospores
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alcohols (ethanol, isopropanol)
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What is an effective form of alcohol?
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60-95%
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The lower the alcohol conc...?
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the higher the exposure time needed
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What is needed for alcohol effectivness?
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water
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What is the action of heavy metals?
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oligodynamic action
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What do heavy metals do?
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denature proteins
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What are some heavy metals?
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AgNO3, CuSO4, Mercurochrome
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What is a skin antiseptic
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mercurochrome
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What are the functions of surface active agents or surfactants
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as a wetting agent to help remove dirt and fats that protect mos, and remove mos from surface
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What does soap do?
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degermine
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What does acid-anionic detergents do?
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sanitizing
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What can soaps do?
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bind oil and water and can wash away bacteria under the oil
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Can antimicrobial soap sterilize
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no
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What can quaternary ammonium compounds do?
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bactericidal and disrupt the plasma membrane
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What is quaternary ammonium compounds effective against?
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enveloped viruses, G+, fungi but not effective against G- and endospores, some bacteria can grow IN them
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What do organic acids do?
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inhibit metabolism (fungi), sorbic acid, benzoic acid, calcium propionate, control molds and bacteria in foods and cosmetics
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What does nitrite do?
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prevents endospore germination (botulism/ clostridium botulina and carcinogens)
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What do antibiotics do?
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nisin and natamycin prevent spoilage of cheese
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What do all meats that show a pink color have?
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nitrite
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What is benzoine used for?
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soda/inhibits yeeast
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What is calcium propionate for?
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on bread to inhibit mold growth
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REVIEW CHARTS
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Graph in notes pg 20
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