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95 Cards in this Set

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