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95 Cards in this Set
- Front
- Back
facultative anaerobe
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A bacterium that carries an aerobic metabolism when oxygen is present but shifts to anaerobic metabolism when oxygen is absent
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exosporium
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a lipid-protein membrane formed outside the coat of some endospores by the mother cell
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serum
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The liquid part of blood after cells and clotting factors have been removed
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mother cell
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(also called parent cell) A cell that has approximately doubled in size and is about to divide into two daughter cells
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medium
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A mixture of nutritional substances on or in which microorganisms grow
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periplasmic enzyme
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An exoenzyme produced by Gram-negative organisms which acts in the periplasmic space
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mesophile
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An organism that grows best at temperatures between 25 and 40 C including most bacteria
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nutritional factor
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One factor that influences both the kind of organisms found in an environment and their growth
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superoxide
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A highly reactive form of oxygen that kills obligate anaerobes
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serial dilution
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A method of measurement in which successive 1:10 dilutions are made from the original sample
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aerotolerant anaerobe
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A bacterium that can survive in the presence of oxygen but does not use oxygen in its metabolism
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microaerophile
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A bacterium that grows best in the presence of a small amount of free oxygen
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alkaliphile
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A base-(alkaline) loving organism that grows beat in an environment with a pH of 7.0 to 11.5
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barophile
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An organism that lives under high hydrostatic pressure
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physical factor
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Factor in the environment, such as temperature, moisture, pressure, or radiation, that influences the kinds of organisms found and their growth
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optimum pH
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the pH at which microorganisms grow best
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generation time
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Time required for a population of organisms to double in number
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conidium
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(plural: conidia) A small, asexual, aerial spore organized into chains in some bacteria and fungi
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colony
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A group of descendants of an original cell
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filtration
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(1) a method of estimating size of bacterial populations in which a known volume of air or water is drawn through a filter with porest to small to allow passage of bacteria. (2) A method of sterilization that uses a membrane filter to separate bacteria from growth media. (3) The filtering of hot water through beds of sand to remove most of the remaining microorganisms aftr flocculation in water treatment plants
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core
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The living part of an endospore
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selective medium
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A medium that encourages growth of some organisims and suppresses growth of others
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capnophile
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An organism that prefers carbon dioxide gas for growth
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dipicolonic acid
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Acid found in the core of an endospore that contributes to its heat resistance
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superoxide dismutase
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An enzyme that converts superoxide to molecular oxygen and hydrogen peroxide
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stationary phase
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The third of four major phases of the bacterial growth curve in which new cells are produced at the same rate that old cells die, leaving the number of live cells constant
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direct microscopic count
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A method of measuring bacterial growth by counting cells in a known folume of medium that fills a specially calibrated counting chamber on a microscope slide
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nonsynchronous growth
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Natural pattern of growth during the log phase in which every cell in a culture divides at some point during the generation time, but not simultaneously
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sapremia
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A condition caused when saprophytes release metabolic products into the blood
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obligate psychrophile
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An organism that cannot grow at temperatufes above 20 C
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nutritional complexity
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The number of nutrients an organism must obtain to grow
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stock culture
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A reserve culture used to store an isolated organism in pure condition for use in the laboratory
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agar
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A poly saccharide extracted from certain marine algae and used to solidify medium for the growth of microorganisms
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preserved culture
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A culture in which organisms are maintained in a dormant state
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turbidity
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A cloudy appearance in a culture tube indicating the presence of organisms
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catalase
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An enzyme that converts hydrogen peroxide to water and molecular oxygen
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hydrostatic pressure
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Pressure exerted by standing water
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casein hydrolsate
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A substance derived from milk protein that contains many amino acids; used to enrich certain media
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sporulation
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The formatino of spores such as endospores
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facultative
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Able to tolerate the presence or absence of a particular environmental condition
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cortex
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A laminated layer of peptidoglycan between the membranes of the endospore septum
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chocolate agar
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Type of medium made with heated blood, so named because it turns a chocolate brown color
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psychrophile
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A cold-loving organism that grows best at temperatures of 15 to 20 C
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obligate
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Requiring a particular environmental condition
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most probable number (MPN)
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A statistical method of measuring bacterial growth, used when samples contain too few organisms to give reliable measures by the plate-count method
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microbial growth
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Increase in number of cells, due to cell division
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obligate anaerobe
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A bacterium that is killed by free oxygen
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obligate thermophile
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An organism that can grow only at temperatures above 37C
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obligate aerobe
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A bacterium that must have free oxygen to grow
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standard bacterial growth curve
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A graph plotting the number of bacteria versus time and showing the phases of bacterial growth
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defined synthetic medium
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A synthetic medium that contains known specific kinds and amounts of chemical substances
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extrachromosomal resistance
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Drug resistance of a microorganism due to the presence of resistance (R) plasmids
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vitamin
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A substance required for growth that the organism cannot make
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aseptic technique
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A set of procedures used to minimize chances that cultures will be contaminated by organisms from the environment
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log phase
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Second of four major phases of the bacterial growth curve, in which cells divide at an exponential or logarhythmic rate
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peptone
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A product of enzyme digestion of proteins that contains many small peptides; a common ingredient of a complex medium
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facultative thermophile
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An organism that can grow both above and below 37C
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countable number
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A number of colonies on an agar plate small enough so that one can clearly distinguish and count them (30 to 300 per plate)
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acidophile
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An acid-loving organism that grows best in an environment with a pH of 4.0 to 5.4
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tetrad
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Cuboidal groups of four cocci
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spore coat
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A keratinlike protein material that is laid down around the cortex of an endospore by the mother cell
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propionibacteria
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Pleomorphic, irregular, nonsporing, gram-positive rods
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differential medium
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A growth medium with a constituent that causes an observable change (in color or pH) in the medium when a particular chemical reaction occurs, making it possible to distinguish between organisms
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trace element
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Minerals, such as copper, iron, zinc, and cobalt ions, that are required in minute amounts for growth
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thermophile
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A heat-loving organism that grows best at temperatures from 50 to 60 C
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cyst
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A spherical, thick-walled cell that resembles an endospore, formed by certain bacteria
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streak plate method
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Method used to prepare pure cultures in which bacteria are lightly spread over the surface of agar plates, resulting in isolated colonies
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halophile
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A salt-loving organism that requires moderate to large concentrations of salt
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neutrophil
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(also called polymorphonuclear leukocyte, PMNL) A phagocytic leukocyte
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decline phase
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(1) The fourth of four major phases of the bacterial growth curve in which cells lose their ability to divide (due to less supportive conditions in the medium) and thus die (also called death phase). (2) In the stages of a disease, the period during which the host defenses finally overcome the pathogen and symptoms begin to subside
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complex medium
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(also called chemically nondefined medium) A growth medium that contains certain reasonably well-defined materials but that varies slightly in chemical composition from batch to batch
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agar plate
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A plate of nutrient medium solidified with agar
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codon
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A sequence of three bases in mRNA that specifies a particular amino acid in the translation process
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synchronous growth
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Hypothetical pattern of growth during the log phase in which all the cells in a culture divide at the same time
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daughter cell
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One of the two identical products of cell division
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plasmolysis
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Shrinking of a cell, with separation of the cell membrane from the cell wall, resulting from loss of water in a hypertonic solution
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enrichment medium
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A medium that contains special nutrients that allow growth of a particular organism
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pure culture
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A culture that contains only a single species of organism
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budding
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Process that occurs in yeast and a few bacteria in which a small new cell develops from the surface of an existing cell
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pour plate method
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Method used to prepare pure cultures using serial dilutions, each of which is mixed with melted agar and poured into a sterile petri plate
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neutrophile
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An organism that grows best in an environment with a pH of 5.4 to 8.5
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pour plate
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A plate containing separate colonies and used to prepare a pure culture
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endospore septum
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A cell membrane without a cell wall that grows around the core of an endospore
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spread plate method
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A technique used to prepare pure cultures by placing a diluted sample of cells on the surface of an agar plate and then spreading the sample evenly over the surface
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reference culture
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A preserved culture used to maintain an organism with its characteristics as originally defined
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fastidious
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referring to microorganisms that have special nutritional needs that are difficult to meet in the laboratory
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binary fission
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Process in which a bacterial cell duplictes its components and divides into two cells
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facultative psychrophile
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An organism that grows best at temperatures below 20 C but can also grow at temperatures above 20 C
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yeast extract
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Substance from yeast containing vitamins, coenzymes, and nucleosides; used to enrich media
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blood agar
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Type of medium containing sheep blood, used to identify organisms that cause hemolysis, or breakdown of red blood cells
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facultative parasite
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A parasite that can live either on a host or freely
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synthetic medium
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A growth medium prepared in the laboratory from materials of precise or reasonably well-defined composition
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germination
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The start of the process of development of a spore or an endospore
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lag phase
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First of four major phases of the bacterial growth curve, in which organisms grow in size but do not increase in number
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exponential rate
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(also called logarhythmic rate) The rate of growth in a bacterial culture characterized by doubling of the population in a fixed interval of time
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