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.
organisms that do not grow optimally in basic conditions but can tolerate pH in this range
organisms that require a small amount of O2 for growth but are inhibited by the amount of O2 normally present in the atmosphere
organisms that grow better in the presence of O2 but will also grow in its absence ex. e. coli
organisms that cannot survive in the presence of oxygen because it is toxic to them
the characteristic temperature dependence with distinct minimum, maximum, and optimum temperatures for every microbial species
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)
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
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
stains groups of bacteria differently that have different morphological characteristics with respect to cell wall structure and composition.
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
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)
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
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.
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
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
bright field microscopy
produces an image from light that is transmitted through a specimen and utilizes a compound light microscope
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
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
located beneath the stage and collects, controls, and concentrates light from the lamp onto the specimen
part of the substage condenser. it is an aperture that controls the angle of light emerging from the top of the condenser.
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
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
a ruler inside the eyepiece that has gradations corresponding to a specific length
the unit of measure that microorganisms are always measured in, with the exception of viruses
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
a set of procedures necessary to maintain the purity of a culture while working with microorganisms.
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.
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.
colonies that are barely within the limits of resolution of the naked eye and are less than 0.1 mm in diameter
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
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.
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
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
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
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
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
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.
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
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
may make gram positive cell walls more rigid and connects cell wall to the plasma membrane
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