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24 Cards in this Set
- Front
- Back
In what temperature range do most pathogens grow
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30-42 degrees C
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What are psychrophiles
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Bacteria that replicate well at cool, refrigerator temperature, such as Listeria monocytogenes
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What are obligate aerobes
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Require O2 for growth, do not ferment
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What are obligate anaerobes
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O2 is toxic, use fermentative metabolism
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What are Microaerophilic bacteria
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Grow best with small amounts of O2. Conduct respiration and fermentation
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What are facultative anaerobes
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Grow in the presence or absence of O2. Conduct respiration and fermentation
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What are aerotolerant anaerobes
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Can tolerate small amounts of O2. Use fermentation only
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What does it mean to have a CO2 requirement
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Capnophilic organisms grow best with elevated CO2 (pulmonary pathogens)
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What are some enzymes that inactivate toxic forms of oxygen
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Superoxide dismutase, Catalase, Peroxidase
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Is moisture required for all bacteria
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Universal requirement for vegetative growth, but not for endospores and some stationary phase cells
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What nutrients are required for bacteria
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Carbon, Nitrogen mainly; also iron, sulfur, phosphorus, and trace elements
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What does it mean for a pathogen to be fastidious
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They require additional nutrients from host, such as hemin or vitamins
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What are the characteristics of fermentation
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Does not require O2; molecules are reduced to pyruvate; pyruvate is reduced to organic acids, alcohol, and gases
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What are the characteristics of oxidative metabolism
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Produces more energy than fermentation; pyruvate enters the TCA cycle and generates 4CO2, 1FADH2, 6NADH, 2GTP; Aerobic respiration follows, generating a total of 38 moles of ATP per glucose
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What is anaerobic respiration
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A modified electron transport cascade that utilizes an alternative molecule as the terminal electron acceptor
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What is cultivation
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Most pathogenic bacteria can be grown in synthetic media
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What are the growth phases of bacteria
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Lag phase, Exponential phase, Stationary phase, Decline phase
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How is bacterial growth measured
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Viable cell counts; Optical density; Detection of metabolic by-products
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Define sterilization
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Use of physical or chemical means to destroy all microbial forms, including vegetative cells and spores
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Define Pasteurization
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Use of heat at high temperatures to rid potable liquids of vegetative bacterial cells
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Define disinfection
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Use of physical or chemical means to destroy most bacterial cells and spores. Not as thorough as sterilization
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Define antisepsis
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Use of chemical agents on the skin or other tissues to remove or inhibit bacterial agents
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If you hoped to assess whether a particular strain of bacteria produced spores, in what phase of growth would you attempt to detect them
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The decline phase
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Why do you suppose a culture of fermentative bacteria smells so foul after several hours of incubation
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Pyruvate is reduced to organic acids, alcohol, and gases
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