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57 Cards in this Set
- Front
- Back
Agents that kill microbes or inhibit their growth are known as ________.
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Antimicrobial agents
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The removal or destruction of all forms of microbial live ,including endospores, is called ________.
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Sterilization
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The technique used to kill Clostridium botulinum and it's spores but is not a complete sterilization is called ______.
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Commercial sterilization
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What is sanitization?
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The reduction of micobes that are present to safe levels.
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What is the term given to a technique of controling microbes that actually kills the microbes?
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Microbicidal agent
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What is the practical use of Commercial sterilization?
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A method used to process canned foods.
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What are the three different approaches to controling microbial growth?
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1)Killing microbes, 2)Preventing microbial growth, 3)Physical removal of microbes
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What is the effect of microbistatic agent?
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As long as the agent is present the growth of the microbe is halted-they inhibit microbial growth.
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Antisepsis is the destruction of vegetative pathogens where?
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On skin and other living tissues.
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Destruction of vegetative pathogens present but does not kill spores is known as ______.
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Disinfection
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What is the term given to the complete absence of microbes from an area?
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Asepsis
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The removal of microbes from an area (such as skin or table)
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Degerming
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A strong, harsh chemical agent used to destroy vegetative pathogens on nonliving surgaces is known as a _______.
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Disinfectant
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What is an Antiseptic?
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A chemical agent that is used to kill vegetative pathogens on living tissue, it is less harsh than a disinfectant.
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Breifly list three reasons for controlling microbial growth.
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1)prevent food spoilage, 2)prevention of desease by microbes, 3)prevention of microbial contamination and undesirable alteration of materials.
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Of the folowing which is the most resistant to anti microbial agents: Naked virus, endospores, prions.
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prions
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Of the folowing which is the most resistant to anti microbial agents: vegetative protozoa, enveloped viruses, mycobacteria.
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mycobacteria
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Of the folowing which is the most resistant to antimicrobial agents: Gram-positive bacteria, Enveloped viruses, Fungi.
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Fungi
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What is the most resistent pathogen?
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Prions
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What is the least resistant pathogen.
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Enveloped viruses.
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Why do we wash and scrub our hands even we use soap?
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It reduces the concentration of microbes present therefore reducing the concentration of of antimicrobial agent needed.
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Why is it better to use hot water when using a chemical agent?
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Heat generally increases the activity of a chemical agent.
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What are five factors effecting the use of microbial chemical agents?
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1)type of pathogen 2)number of microbes present 3)concentration of chemical agent 4)Time of exposure 5)environmental conditions
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What is the ideal concentration of a chemical agent and why?
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Lowest effect concentration because it is the most cost effective and the least toxic.
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List some environmental conditions that effect the activity of chemical agents?
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pH, temperature, organic molecules(mucus, fecal matter, blood)
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How does decreasing pH effect the activity of a chemical agent?
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Acidity generally increases activity of chemical agents.
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How is time of expsoure related to activity of chemical agents?
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time os exposure is inversely related to the concentration of the chemical agent and directly related to the number of microbes present.
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Are cold temperatures microbicidal or microbistatic?
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Microbistatic-cold temperature don't kill the microbes they just halt their growth.
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Desiccation is microbicidal. True or False?
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False-desiccation only halts growth.
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What are the three targets by which chemical agents affect microbes?
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1)cell membranes 2)proteins 3)nucleic acids(DNA)
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What are the targets of phycisal factors that affect microbial growth?
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1)cell membranes 2)proteins 3)nucleic acids(DNA)
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What effect does exposing microbes to steam heat have and is it microbistatic or microbicidal?
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Steam heat causes cellular components to coaggulate and it is microbicidal.
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Is dry heat microbicidal or microbistatic and how does exposure to it affect microbe?
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Dry heat bakes or oxidizes(burns or incinerates)cell components and it is microbicidal.
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A disinfecting process uing high temperatures to kill all pathogens present in foods is known as _________.
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Pasteurization
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What are the different types of pasteurization?
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1)classic method of pasteurization 2)high temp short time 3)ultra high temp
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Describe the classic method of pasteurization?
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Exposure substance to 63C for 30 mins
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Explain the difference between the Classic method of pasteurization and the HTST method.
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The HTST method has higher temperatures and shorter times and is considered equivelent methods if they kill all the microbes present.
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Does steam or dry heat kill quicker and how?
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Steam heat kills quicker by penetrating the cellular components and coaggulating then or clumping them together.
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What are equivalent treatments?
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methodes of changing temperature and varyinge exposure times to acquire the same results as the classic method of pasteurization.
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What do we call the minimum time required to kill microbes present in a suspension or liquid at a given temperature?
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Thermal death time
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What is the decimal reduction time?
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the time required to kill 90% of the bacteria present at a given temperature.
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What do we use to kill microbes by producing high-energy free radicals which react with DNA and other components killing microbes?
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Ionizing radiation
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What is a practical use for the killing of microbes by exposing them to ionizing radiation?
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Cold sterilization
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Killing microbes in foods by the use of ionizing radiation is called _______.
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cold sterilization
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What are the two types of filters used to remove microbes and what are the mediums they work on?
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HEPA filters-removes microbes from the air and Membrane filters-that remove microbes from fluids.
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What does HEPA stand for?
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High-Efficiency Particulate Air
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What is the best way to sterilize a heat sensitive fluid
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By using a membrane filter.
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Describe the process of lyophilization.
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Freeze drying of microbial cultures in a vaccum (water is removed by sublimation)
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What is a common way of storing microbes by using both cold temperatures and dessication.
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lyophilization
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What is the term given to the removal of water and it is ti microbicaidal or microbistic?
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Dessication-and its microbistatic
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What are the typical conditions of an autoclave?
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15 psi. steam pressure at 121C for 15 minutes.
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How does high pressure effect microbial growth.
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It kills them by altering and denaturing their proteins
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List the six methods of physical control of microbial growth?
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1)heat 2)cold 3)filtration 4)high pressure 5)desiccation 6)radiation
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What are the typical conditions for sterilization with dry heat and what is it used for?
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170C for 2hrs.-used to sterilize glassware.
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What kind of sterilization do we use to sterilize our inocculation loops in lab?
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Dry heat-incineration-oxidizing of cellular components.
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What is the term given to the physical removal of microbes?
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filtration
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What type of fluids are best suited for filtration rather that pasteurization?
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vitamins and antibacterial fluids that will be destroyed by heat
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