Download UTC Microbiology - Lab Midterm Question and answer verified to pass 2025 and more Exams Microbiology in PDF only on Docsity!
UTC Microbiology - Lab Midterm
Question and answer verified to pass
anionic stains; won't directly stain bacterial cells, and are useful for revealing the outlines of bacterial cells (stain the background) - correct answers eosin and nigrosin crystal violet, methylene blue; useful for direct staining of the cells - correct answers cationic dyes implies the use of only a single stain, which is usually sufficient to reveal the bacterial basic morphology (size, shape, and characteristics) - correct answers simple staining reveal more specialized bacterial morphological features; used to distinguish between the vegetative cells and the endospores - correct answers differential staining differential stain that can divide bacteria into two major groups; used to distinguished between bacteria with different cell wall characterisitics - correct answers gram stain 1 meter - correct answers 1000 millimeters 1 millimeter - correct answers 1000 micrometers 1 micrometer - correct answers 1000 nanometers
the clamping device that secures and moves the slide while it rests on the stage - correct answers mechanical stage located under the left side of the stage; move the slide horizontally (lower knob) and vertically (upper knob) - correct answers mechanical stage control knobs there are 3; the eyepieces (ocular), the objectives(3-4) and the condenser - correct answers lens systems ocular, magnification is constant (10x) - correct answers eyepieces there are 3-4 of them; 10x, 40x, 100x -are arranged on a revolving nosepiece so that they can be rotated into the line between the eyepiece and specimen. -A prism in the tube bends the light so the user can view specimens while seated - correct answers objectives total magnification - correct answers power of the ocular X power of the objective lens that serves to concentrate light from the illumination source that is in turn focused through the object and magnified by the objective lens; basic component of almost all compound light microscope - correct answers condenser causes a relatively large movement of the stage holding the specimen; used when the microscope is in the low power (10x) objective - correct answers coarse adjustment knob
put on the slide while using the 100x objective to sharpen very zoomed in images - correct answers immersion oil procedures used/performed under sterile conditions, includes lab techniques to keep bacteria pure -required to transfer a pure culture from one type of media to another - correct answers aseptic technique instrument for sterilization by means moist heat under pressure (121 degrees C (250 degrees F)) - correct answers autoclave specific type of medium; comes in a powder form, water or other medium is added to solidify (it solidifies at low temps) - correct answers agar medium used in lab 2; composition: pancreatic digest of casein, agar, NaCl, papaic digest of soybean meal, K2HPO4, glucose at pH of 7.3, 25 degrees celcius - correct answers trypticase soy agar what should be written on all labels for tubes, dishes, etc. - correct answers organism, type of medium, date, name, course the optimal growth temperature for E. coli and M. Luteus (lab 2) - correct answers 37 degrees celsius types of media - correct answers solid, broth, semi solid, slant concept that evolved in the 19th century to prevent the spread of bacterial infection - correct answers asepsis
showed that washing hands prior to delivery reduced childbirth fever - correct answers semmelweis contains nutrients and physical growth parameters necessary for microbial growth; can be distinguished on the basis of composition, consistency and purpose - correct answers culture media contains agar at a concentration of 1.5-2.0% or some other, mostly inert, solidifying agent; has structure and allows bacteria to grow in physically informative or useful ways ( colonies, streaks, etc) -used to fine pure cultures - correct answers solid medium prepared with agar at concentrations of 0.5% or less; they have a soft, custard like, consistency and are useful for the cultivation of microacropilic bacteria or for determination of bacterial motility - correct answers semisolid media contains specific amounts of nutrients but don't have trace of solidifying agents, like agar; serves various purposes such as the propagation of large numbers of organisms, fermentation studies, etc. -mixed organisms cannot be separated - correct answers broth media turbid - correct answers state of organisms in broth in which organisms are diffused uniformly throughout the broth sediment - correct answers some organisms will sink to the bottom of broth and form a: sediment pellicle - correct answers some organisms in broth will grow in clumps, producing flocculent growth and some will float on top, forming a:
pigmentation-pale optical property-translucent - correct answers characteristics of E. Coli form, margin, and elevation in solid media - correct answers colony morphology forms of bacteria in solid media - correct answers circular, irregular, filamentous, rhizoid elevations of bacteria in solid media - correct answers raised, convex, flat, umbonate, crateriform forms of bacteria in solid media - correct answers entire, undulate, filiform, curled, lobate most common bacterial growth patterns on an agar slant: - correct answers filiform, spreading, beaded, filamentous
- correct answers coccus
- correct answers streptococcus
- correct answers staphylococcus
- correct answers sarcina arrangements of cocci - correct answers coccus, diplococcus, streptococcus, tetrad, staphylococcus, sarcina
- correct answers coccobacillus
- correct answers bacillus
- correct answers diplobacilli
- correct answers palisades
- correct answers streptobacilli arrangements of bacilli - correct answers coccobacillus, bacillus, diplobacilli, palisades, streptobacilli differential staining technique used to distinguish between vegetative cells and endospores - correct answers schaeffer-fulton method malachite green - correct answers what is the stain used for endospores heat - correct answers what is the mordant in endospore staining water - correct answers what is the decolorizer in endospore staining vegetative cells - correct answers when water is used in endospore staining what cells lose the stain? safranin - correct answers what is the secondary stain in endospores
acids, gases, and other specific molecules - correct answers many media and tests have been developed to identify specific types of bacterial fermentation and the types of __________ that are produced, such as:__________ breakdown of carbohydrate molecules to produce energy; allows bacteria to grow and multiply, other products may be acidic or non-acidic and may include CO2 - correct answers carbohydrate metabolism acid and gas production; analyzed by inoculating bacteria into a broth with phenol red pH indicator and lactose, bacteria where this occurs will grow and produce acid and gas (which is caught in an inverted durham tube) -turbidity=growth - correct answers lactose fermentation growth with non acidic metabolic products - correct answers fermentation test: turbidity + red medium = bubbles in durham tube - correct answers what indicates production of CO2 in fermentation phenol red - correct answers what is the pH indicator for fermentation yellow - correct answers In a fermentation test the medium will turn _______ in the presence of acid tested positive for acid and gas production in lactose fermentation procedure - correct answers E. Coli fermentation tested negative for acid and gas production in lactose fermentation procedure
- correct answers P. aeruginosa fermentation
used to determine whether or not certain bacteria can meet its energy and carbon requirements by its metabolism of this particular compound; used to diagnose members of the enterobateriaceae family - correct answers citrate bromthymol blue - correct answers what is the pH indicator in Simmon's agar for citrate? green to blue - correct answers growth of microorganisms on Simmon's agar for citrate changes color from________ to __________ tests negative for citrate utilization - correct answers E. coli citrate test results tests positive for citrate utilization; turns simmon's citrate agar blue - correct answers E.aerogenes citrate test results proteins amino acids inoculation proteins - correct answers some bacteria have the genetic code to produce enzymes to break down _________ into __________. This can be determined in the lab by __________ into defined media containing specific __________ then analyzing the results after incubation. produced by many organisms, a proteolytic enzyme that catalyzes the hydrolysis of the protein, gelatin (collagen); the test is used as a way to look at the proteolysis in bacteria and it detects the ability of the bacteria to produce the enzyme. -the hydrolysis of gelatin production. - correct answers gelatinase
permit the isolation of specific groups of microorganisms; special chemicals are added that allow certain types of organisms to grow, while inhibiting the growth of others
- is achieved by adding dyes, antibiotics, salts, or inhibitors which affect the metabolism or enzyme systems of the organisms - correct answers selective media used to differentiate closely related organisms or groups of organisms; same plate, certain dyes or chemicals are incorporated into the media that allow visual of characteristic changes or growth patterns that allow for identification - correct answers differential media organisms that require enriched media and a controlled atmosphere in order to grow; "picky" - correct answers fastidious organisms selective and differential media: -inhibits growth of gram + -contains bile salts and crystal violet -lactose and neutral red are added to differentiate lactose fermenters (pink colonies) from non fermenters - correct answers MAC gram negative rods - correct answers MAC detects growth of gram positive -due to crystal violet and bile salts in medium - correct answers MAC inhibits selective of staphylococcus, but can still be differential: -contains 7.5% salt, which kills off most bacterias
-manitol= sugar that is used to differentiate types of staphylococcus by their ability to break it down - correct answers MSA 7.5% - correct answers MSA contains ______ salt, which kills off bacteria 1.5% - correct answers most bacteria prefer around _____ NaCl selective and differential: -eosin and methylene blue= dyes that make it selective of gram - -lactose= ability to ferment differentiates different types of gram - (if acid and gas are produced, it turns yellow) -ex. E. coli has naturally occuring lactase (so it'll break down lactose) - correct answers EMB gram negative bacteria - correct answers EMB promotes growth of gram positive bacteria - correct answers EMB inhibits growth of enriched differential; TSA with sheep blood that enriches bacteria (concentration of 5-10%) -used to isolate fastidious organisms and detect hemolytic activity (blood cell breakdown)
- beta, alpha, gamma - correct answers blood agar complete breakdown of red blood cells and surrounding colonies - correct answers beta hemolysis
required to transfer a pure culture from one type of media to another- the microbiologists means taking all prudent cautions to prevent contamination of the culture and spreading of micro into the environment." - correct answers Describe the purpose of aseptic technique in the micro lab' To identify separate colonies/ pure culture - correct answers What's the purpose of the streak plate technique you performed last week? solidifying agent only - correct answers Agar is added to microbiological media as? cell wall - correct answers Gram stain is a differential staining procedure used to distinguish between bacteria based on their. primary stain stains all bacteria purple - correct answers What is crystal violet and what is its function 1 minutes - correct answers how long does crystal violet stay on a smear? The plates must be incubated inverted so condensation doesn't drip onto the bacteria and disturb growth. - correct answers Why must plates be incubated inverted or upside down? mordant fixes primary stain to Gram-Positive bacteria - correct answers What is iodine and what is its function 1 minute - correct answers How long does iodine stay on the smear
decolorizer removes stain from Gram-negative bacteria - correct answers what is alcohol and what is its function 15 seconds - correct answers how long does alcohol stay on the smear counterstain stains all gram negative bacteria pink - correct answers what is safranin and what is its function 1 minute - correct answers how long does safranin stay on the smear Endospores resist staining so heat is required - correct answers Why is heat necessary in spore- staining procedure? to decolorize the cells - correct answers What is the function of water in spore- staining procedure? the purpose of using mordant is to hold the crystal violet stain to the gram positive bacteria - correct answers explain the purpose of using a mordant in gram staining The ethanol is left on for too long so it strips off the crystal violet from the gram pos bacteria so when you wash it all the crystal violet washes out and it becomes stained by the safranin. - correct answers Gram pos bacterial cells appear pink after finishing a gram stain. Explain the color.
