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44 Cards in this Set
- Front
- Back
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Bacterial cell growth involves?
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Polymerization reactions
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Bacterial cell growth continues until?
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the cell divides by binary fusion
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An increase in the number of microbial cells in a population is defined as?
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Population Growth
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The time required for a cell to divide and its population to double is called?
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generation time
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When the number of cells in each generation is expressed as a power of 2, the exponent tells the number of doublings that have occurred this is known as?
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Exponential growth
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What is the bacterial growth curve?
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produced when a population of bacterial cells are grown in a test tube
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What is a "closed culture"?
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When no new nutrients are added to the growth environment
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Period of little or no cell division is called?
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Lag phase
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Exponential growth phase
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log phase
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period of equilibrium in cell growth
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stationary phase
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when number of deaths exceeds the number of new cells formed
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Death phase
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A culture that allows maintenance of cell population in exponential phase for long periods
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Continuous culture
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Most common reaction vessel in a continuous culture
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Chemostat
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What is the effect of temperature on organism growth?
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Each organism has a set of "cardinal temperatures"
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What are the three temperature ranges for organisms growth?
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Minimum, Maximum, and Optimum
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Organisms are grouped together by which temperature setting?
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Optimum growth
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Optimum temperatures are marked by what?
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best for metabolic processes, most rapid growth, always closer to maximum than minimun
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Three primary classifications based on tempertures
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Psychrophiles (cold loving) mesophiles (moderate temp) and thermophiles (heat loving)
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Two types of psychrophiles
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Obligate and facultative Psychrophiles
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What is a facultative psychrophile
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will function at zero but have a higher optimum temp than obligate
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All organisms that are pathogenic to humans are of type?
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Mesophiles
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What is the optimum temp for Mesophiles
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20-40 celcuis
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Microorganisms capable of growth at high temperatures are called?
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Thermophiles
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What are thermophiles that love extreme temps called?
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Hyperthermophiles
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Microorganisms usually cause changes in ___ of the enviroment as they grow
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pH
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Which organisms grow at low pH
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Acidophiles
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Which organisms grow at higher pH?
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Alkalinophiles
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Water availability is dependent on
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Water content of environment and presence of solute
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What are the 5 classifications based on water needs?
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Obligate, Halophiles, Facultative Halophiles, Osmophiles, and Xerophiles
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Obligate Haolphiles require what for growth?
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high salt concentrations
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Which organisms live optimally at water activity of sea water?
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Halophiles
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Which organisms can give in environments high in sugar?
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Osmophiles
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Which organisms can only obtain water by increasing their internal solute concentration?
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Xerophiles
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Which organisms use oxygen as the final electron acceptor in metabolism
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Aerobes
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Three types of Aerobes?
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Obligates aerobes must have O2, Microaerophilic, require O2 but lower than atomspheric pressure and Facultative Anaerobes primary aerobes but will do anaerobic if forced
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All three groups of aerobes have enzymes for breaking down toxic forms of oxygen such as?
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Superoxide dismutase and catalase
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Two types of Anaerobes?
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Aerotolerant Anaerobes, and Obligate anaerobes, are killed when exposed to O2
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Nutrients needed by microorganisms include:
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Major elements (SPONCH) and minor elements Na and Cl, K Mg and Fe Ca
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This indicates the number of nutrients an organism must obtain to grow
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Nutritional complexity
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Nutritional complexity is determined by?
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kinda and number of enzymes the organism has
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A high nutritional complexity reflects a?
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deficiency in biosynthetic enzymes
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when an organism has enzymes to synthesize needed nutrients it is said to be?
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Low Nutritional complexity
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When and organism must be given preformed molecules it is said to be?
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High nutritional complexity
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3 ways microorganisms adapt to limited nutrients
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increase synthesis of enzymes needed, synthesis of enzymes need to use a different nutrient, and decreased metabolic and growth rates
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