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122 terms

howard micro

organisms that can grow over a wide range of water activity or osmotic concentrations
organisms that grow optimally in high salt concentrations
organisms that can tolerate high levels of salt but do not grow optimally in them
organisms that grow optimally in high sugar concentrations
where the cell membrane pulls away from the cell wall. this results in dehydration in many organisms and growth ceases. it happens in hypertonic solutions when water exits the cell, causing the cell to shrink. osmotolerant organisms have mechanisms that prevent their proteins from aggregating in hypertonic environments.
organic compounds that accumulate in the cytoplasm and act as solutes that balance the osmotic pressure.
antibiotic resistance
pump toxin out of cell
organisms that grow optimally between pH 0 and pH 5.5
organisms that can tolerate acidic pH even though growth is not optimal there
organisms that grow optimally between pH 5.5 and pH 8.0
organisms that grow optimally between pH 8.5 and pH 11.5
organisms that do not grow optimally in basic conditions but can tolerate pH in this range
obligate aerobes
organisms that will only grow in the presence of O2
organisms that require a small amount of O2 for growth but are inhibited by the amount of O2 normally present in the atmosphere
facultative anaerobes
organisms that grow better in the presence of O2 but will also grow in its absence ex. e. coli
aerotolerant anaerobes
organisms that grow equally in the presence or absence of oxygen
obligate anaerobes
organisms that cannot survive in the presence of oxygen because it is toxic to them
organisms that require elevated levels of CO2 for optimal growth
produces methane
cardinal temperatures
the characteristic temperature dependence with distinct minimum, maximum, and optimum temperatures for every microbial species
growth is the best/fastest/most efficient
organisms that grow optimally at cold temperatures between O degrees C and 15 degrees C
organisms that do not grow optimally at cold temperatures but will exhibit some growth at these temperatures. these organisms include many organisms responsible for food spoilage, like lactic acid bacteria
grow optimally at ambient temperatures between 20 and 40 degrees celsius. many organisms in our lab fall into this range. (also human inhabitants and pathogens)
grow optimally at warmer temperatures between 50 and 80 degrees celsius
organisms that do not grow optimally in warmer temperatures but are able to survive them (ex. endospore formers)
organisms that grow optimally in extremely hot temperatures, above 80 degrees celsius (ex. archaea)
a dormant form of bacteria that produce them, which allow bacteria to survive harsh conditions including temperatures, chemicals, irradiation, pH changes, and dessication. endospores are produced within the cells in a process called sporulation
vegetative cells
metabolically active cells, cells that are capable of growth and reproduction
structural stains
stains used to classify or assist in identifying organisms based on the presence or absence of specific structures
negative structural stain
a stain that requires the background to be contrasted with the capsule in order to visualize it.
a structure that is composed of polysaccharides or polypeptides that are mucoid and give cells a sticky outer surface
capsules that are composed of polysaccharides, means sugar shell
acid-fast stain
stains groups of bacteria differently that have different morphological characteristics with respect to cell wall structure and composition.
mycolic acids
contained in the cell wall of acid-fast bacteria which are waxy substances that lead to differences in staining behavior. they confer a higher affinity for the primary stain used and also add resistance to decolorization
gram stain
the staining procedure used most often in microbiology that is based on morphological characteristics with respect to cell wall structure.
gram + bacteria
possess a thick cell wall composed of many interconnecting layers of peptidoglycan. it contains teichoic acids which increase the degree of cross-linking between peptidoglycan layers
gram - bacteria
posess a thin layer of peptidoglycan only a few layers thick and lack teichoic acids in their cell wall. the cell walls have a lesser degree of cross-linking and possess an outer membrane that surrounds the cell wall which is composed of lipopolysaccharides (LPS)
acidic dyes
utilized when performing negative stains (congo red and nigrosin). they contain negatively charged chromophores which are repelled by cellular surfaces that are negatively charged, and therefore stain the background
negative stains
results in a colored background while the cells remain clear. it does not involve heat-fixing specimens, and is used when the sample is too delicate to withstand heat-fixing.
basic dyes
utilized when performing positive stains (crystal violet, methylene blue, safranin). they contain positively charged chromophores which are attracted to cellular surfaces that are negatively charged, and therefore stain the cells
positive stain
results in colored cells against a clear background. it involves heat-fixing specimens which kills the bacteria and helps them adhere to the slide, making it easier to stainthe specimen without washing it away. heat-fixing can sometimes distort cell shape
random clusters
micro (tetrad)
square groups of 4 cells
cubical groups of 8 cells
bright field microscopy
produces an image from light that is transmitted through a specimen and utilizes a compound light microscope
compound light microscope
contains two types of lenses where specimens are magnified
concentrates the light on the specimen
objective lense
the first place the specimen is magnified. usually 4x, 10x, 40x, 100x
the image should remain in focus when switching between objective lenses
ocular lense
inside the eyepiece, it magnifies the image a second time by a power of 10x. this creates a virtual image of the specimen that appears below or within the microscop
total magnification
the magnification of the objective lens in use multiplied by the magnification of the ocular lens
the clarity of an object. the limit is the length two points must be away from each other in order to be viewed as separate. light miscroscopy can not distinguish between two points that are closer together than 0.2 micrometers
0.2 micrometers
the limit for a light microscope
dial that controls the intensity of the light coming through to the specimen
substage condenser
located beneath the stage and collects, controls, and concentrates light from the lamp onto the specimen
iris diaphragm
part of the substage condenser. it is an aperture that controls the angle of light emerging from the top of the condenser.
numerical aperture
measure of a lenses ability to capture light coming from the specimen and use it to make the image. it indicates the resolving power of the lens
immersion oil
used with the 100x objective lens. it allows more light to pass through to the specimen since it has a higher refractive index than air. less light is scattered by refraction. it improves the numerical aperture of the lens and increases resolution
ocular micrometer
a ruler inside the eyepiece that has gradations corresponding to a specific length
stage micrometer
contains a ruler on a slide with gradations of a known width.
the unit of measure that microorganisms are always measured in, with the exception of viruses
the process of growing organisms on media under controlled laboratory conditions
can use visible light from the environment to create ATP
require chemicals in the media that they can break down from ATP
macronutrients needed by cells
a polysaccharide from seaweed that is not metabolized by most microorganisms. it does not provide any nutrients for organisms but can serve as a solid surface for colony growth
aseptic technique
a set of procedures necessary to maintain the purity of a culture while working with microorganisms.
streak plate
allows one to isolate individual cells from a pure or mixed culture. performed on solid media contained in petri dishes. they are often used to analyze colony morphologies of organisms.
pure culture
contains only one species
a large number of bacterial cells on a solid medium that is visible to the naked eye as a discrete entity. all cells are genetically identical.
colony form
refers to the shape of a colony
colony elevation
refers to the presence and type of height
colony margin
refers to the edge of the colony
colonies that are barely within the limits of resolution of the naked eye and are less than 0.1 mm in diameter
organisms that form colonies greater than 4 mm within 48 hours
organisms that spread from the original locations on an agar plate as slightly raised, concentric waves of thin filmy growth over large surface areas of the medium after short periods of incubation
surface texture
can be described as smooth or wrinkled
surface appearance
describes how light bounces off the colony, can be dull, shiny, or glistening
mold colony
will appear cotton-like and "fuzzy"
quadrant method
involves using four areas on a solid surface to create a dilution gradient where cells are separated more and more in each quadrant. many streaks are performed to dilute the culture slowly, and the stock culture is used only once.
cloudiness in the broth
formed by organisms that are non-motile and will sink to the bottom of the tube in a broth culture
formed by organisms that grow better in the presence of oxygen or require oxygen for growth which will grow at the top of the test tube where the concentration of oxygen is greatest
growth where organisms appear as clumps in the broth
broth culture
used to grow organisms quickly and in large amounts for immediate use. can be used to observe growth patterns or to perform additional tests on organisms
slant culture
used to store already purified cultures for extended periods of time. can be sub-cultured to broths or new slants if needed for further study or testing
process used by organisms to generate energy from food
true motility
individual cells exhibit independent movement over large distances. the movement often described as non-random and with a purpose, and is usually due to the presence of extracellular appendages that enable the organisms to travel in the environment autonomously
the appendage responsible for bacterial movement. in prokaryotes, it moves in a spinning motion and results in a characteristic tumble and run pattern
brownian motion
sometimes confused for true motility but is not actually a result of self-directed movement by the cell. it si a result of collisions with water molecules, organisms appear to be jiggling and not moving over large distances
wet mount
constructed by placing an aqueous sample of a specimen on a microscope slide and covering it with a cover slip. viewed with as little illumination as possible in order to improve the contrast.
hanging drop
contructed by placing an aqueous sample of a specimen on a cover slip and placing it on top of a washer. the sample will hang from the cover slip. they are a little more difficult to focus because they are three dimensional
the portion of a dye that confers color. it can be positively or negatively charged which influences the type of staining pattern achieved
cellular morphology
cell shape and cell arangement
species that have a variety of shapes
how individual cells are oriented with each other
kills the bacteria and helps them adhere to the slide, making it easier to stain the speciment without washing it away. however it can distory cell shape
used to bind to the crystal violet to form an insoluble complex
used to remove dye from certain cells.
curved rod
short rod
rigid spiral
flexible spiral
describes an organism that remains attached to a surface for its entire life
a tiny cell that is able to grow into a new organism
the total mass of living matter in a given unit area
A form of a colony where the growth is most dense in the middle, and branches outward
teichoic acids
may make gram positive cell walls more rigid and connects cell wall to the plasma membrane
free floaters
is a component of a molecule which causes a molecule to be fluorescent. It is a functional group in a molecule which will absorb energy of a specific wavelength and re-emit energy at a different wavelength
having deeply indented margins but with lobes not entirely separate from each other
process of forming an endospore within a vegetative cell
tryptic soy broth
elevation; raised with a convex center
osmotic pressure
the external pressure that must be applied to stop osmosis
form of growth, rootlike structure
organisms that have strict nutritional requirements