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55 Cards in this Set
- Front
- Back
Three ranges microbes grow in:
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Minimum
Optimum Maximum |
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What is the best growth rate (what range) for microbes?
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At the optimum range.
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Two factors that are required for growth:
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Environmental factors
Nutritional factors |
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Three environmental factors for microbes are:
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1. Temperature
2. pH levels 3. Osmotic Pressure |
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Basic Temperature requirements for: Psychrophiles
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cold loving, under 20 C
important in food storage cause food spoilage in the fridge |
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Basic Temperature requirements for: Mesophiles
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moderate temperature
25-40 C Medically important bacteria are in the Mesophile group optimum at 37 c |
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Basic Temperature requirements for: Thermophiles
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heat loving
grow above 50 C found in hot springs |
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Basic Temperature requirements for: Extreme thermophiles
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Grow beyond 100 C
in sea beds (in hot springs) |
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Four main types of microbes that rely on temperature:
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1. Psychrophiles
2. Mesophiles 3. Thermophiles 4. Exterme thermophiles |
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Prime pH level microbes grow in:
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pH level of 6.5 - 7.5
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Acidophils prefer low pH of:
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3 pH
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Alkaliohilis have a pH of around
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10.5 pH
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What are Halophiles?
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Salt Lovers (microbes that love salt)
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list 6 nutritional requirements:
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Energy source
Carbon Nitrogen, sulfur, phosphorus Oxygen Growth Factors Trace of minerals |
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Nutritional requirements: List 2 Autotrophs and their characteristics
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Photoautotrophs: light + carbon
Chemoautotrophs: inorganic compounds + carbon dioxide |
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Nutritional requirements: Define Chemo - Heterotrophic
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Use organic compunds for energy and carbon source
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What are the two modes of life?
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Saprobes (free living)
Parasites. |
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What are the types of Parasites
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Obligate
Facultative Oligate Intracellular Extracellular |
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Respiration of Microbes: Organic Compounds oxidize to...
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inorganic carbon
(ie. Glucose --> C)2 + H2O + energy (ATP) |
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Fermentation: Organic compounds are partially oxidized to...
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smaller organic compounds
(ie. Glucose --> organic acids, alcohols, CO2 + little energy ATP). |
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Why is Nitrogen needed?
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For protein and nucleic acid synthesis
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How is Nitrogen obtained?
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From NH4+ or NH3-
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What is Nitrogen fixation?
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Bacteria that are capable of elemental Nitrogen (ie. in soil fertility).
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Is O the final electron acceptor in respiration?
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Yes.
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Organisms are classified as 2 things (in terms of oxygen requirements):
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1. Obligate Aerobes
2. Microaerophiles |
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Define Obligate Aerobes:
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-require oxygen
-grow best at atmospheric concetration of oxygen -broth culture will be dense on the surface |
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Define Microaerophiles:
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- require oxygen at a lower concentration than the atmospheric concentration
- abundant growth just below the surface |
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Define Facultative anaerobes:
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Grow in the presence or in the absence of oxygen
broth growth is uniformly distributed throughout |
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Define Aerotolerant anaerobes:
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Do not use oxygen, but can grow in the presence of O
Similar growth pattern like Facultative |
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Define Obligate anaerobes:
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Inhibited by by Oxygen
Growth is limited to the bottom of the tube in a broth culture |
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Define Capnophiles:
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Require increased levels of CO2
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Three systems used for Anaerobic Cultures?
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1. Gas Pak System
(CO2 and H2, methylene blue) 2. Anaerobic chamber (Put arms through, dish one one side) 3. Reducing Medium: Thioglycollate broth (tall test tubes). |
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What are trace minerals required for microbial growth?
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Sulfur, phosphorus and other trace elements
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Bacteria can not synthesize organic growth compounds in:
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vitamins and certain amino acids
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Cell division causes population size of microbes to
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grow.
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Cells divide by:
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binary fission
(single cell divides into 2 idential daughter cells. starts with the chromosome replicating, divide, seperation of daughter cells and then the cytoplasm divides). |
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Exponential growth is when:
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2n is the number of cells.
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For example: Mycobaterium Tuberculosis may take up to ____ hours to double
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24 hours
3 weeks to get visible colonies |
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For example: Escherichia Colia takes about ___ minutes to generate:
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20 minutes
Over night culture gives visible colonies |
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What is involved in the microbial growth curve (4 main areas on the curve)?
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Lag phase
Exponential phase (log phase) Stationary phase Decline (Death) phase |
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What happens in the lag phase of the microbial growth curve chart?
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Adapation and prep. for growth
active metabolic acitivty takes place, prep for cell division no increase in number |
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What does the time depend on, in the Lag Phase?
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the species
environmental conditions (nutrition, temperature, oxygen) |
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What happens in the Log / exponential phase?
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Where cells form (gram stain here, flagella here).
Cells form by start dividing, number increases exponentially Cells are smallest size in this stage and are all at the same physiological stage Cells are sensative to chemicals because they are dividing |
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For example, an antibiotic that inhibits cell wall synthesis that is effective at the lag / exponential phase is known as:
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penicillin
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What happens in the Stationary Phase?
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population growth comes to halt / slows down
some make spores – slow down growth depletion of nutrients, accumulation of toxic products division rate = death rate no increase in cell number cells are at different physiological state |
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What happens in the Death Phase / Decline of the microbial growth curve?
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Death is the failure of a cell to ddivide under optiminal growig conditions
Death rate > division rate Death due to lack of nutrition, accumulation of toxic substances and autolysis |
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What is it called when the culture is kept in log phase in research?
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Known as the "continous culture"
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What is a chemostat?
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keeps adding fresh culture (nutrients) at regular intravals and is continously stirred by sterile air.
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Dead and alive cells are counted in a total count per volume measurement. What is the unit of measurement?
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cell/mL
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Graphs plotted will not show the (2 phases):
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Stationary and Death Phase
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Direct method of measuring microbial growth are:
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Microscopic
Viable Count CoulterCounter Flow cytometer |
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Define the viable count process
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- Culture is on a semisolid surface.
- colonies are counted - Expressed in Colony Forming Unit (CFU). |
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What is done in a coultercounter and flow cytometer?
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count and sort cells.
cytometer counts white and red blood cells in humans (chemical attached to red to see how many are passed through). |
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What are the indirect ways of measuring microbial growth?
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Estimation (optical density and metabolic activity)
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What is done in a Metabolic Activity Estimation process?
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Measure acid production, carbon dioxide production, oxygen consumption, assimilation rate of chemicals, nurtrients from the culture media.
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