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Micro-Lab Pr. 2
| Question | Answer |
|---|---|
| what kind of broth is needed to check temperature? | just a nutrient broth; no special broth needed |
| differential media; used to determine O2 requirements of bacteria; a semi-solid gel with an O2 indicator in the media | thioglycollate broth |
| determines if thioglycollates are active; green=O2, pink=no O2 | resazaurin |
| used to determine how many bacteria are present | quantitative plate count |
| ____ counts are counts that include only "live" bacteria | viable |
| ____ counts are counts that include living and dead bacteria | total |
| a sequence of dilutions using previously diluted solutions to make current solutions; a series of sequential dilutions | serial dilution |
| equipment for quantitative plate counts | stock (bacteria), seven 9-mL sterile water test tubes, eight sterile pipettes, four sterile petri dishes |
| quantitative plant count procedure | transfer 1-mL of stock to tube 1 w/pipette, transfer 1-mL from tube 1 to tube 2 (and so on thru tube 7), transfer 1-mL from tube 4 (w/the original pipette for tube 4) to plate 4 (and so on thru tube 7 to plate 7), add agar to dish 4-7 and swirl gently |
| an increase in the number of cells; cell division | cell growth |
| putting any microbe in or on a media | inoculation |
| bacteria that require total 02; what does it look like in test tube? | strict aerobes; bacteria all the way at top; with a green ring |
| bacteria that require a total absence of O2; what does it look like in test tube? | strict anaerobes; clear at top of specimen, all bacteria below that |
| bacteria that can grow in the presence or absence of O2 and do NOT use O2 for growth; what does it look like in test tube? | aerotolerant anaerobes; cloudy throughout |
| bacteria that grow better in the presence of O2 than no O2; what does it look like in test tube? | facultative anaerobes; looks like a lightning bolt in test tube |
| bacteria that require small amounts of O2 for growth and are killed by "regular" amounts of O2; "mud bacteria" | microaerophiles |
| Why is O2 toxic to some bacteria? | anaerobes lack certain enzymes that are essential for bacteria to survive in presence of oxygen |
| How do aerobic cells deal with toxic O2 compounds (byproducts of aerobic respiration)? | they're eliminated by enzymes (which are commonly found in aerobic bacteria) |
| this procedure is done to ensure that only a limited number of colonies develop in the plate; if too many colonies present on a plate, some cells are overcrowded and do not develop | serial dilutions; quantitative plate count |
| number range of bacteria on a plate appropriate for determining cell count/mL | 30-300 |
| a sealed jar system which uses a foil gas generator, a palladium catalyst, and a methylene blue indicator strip; if microbe grows in this---it is anaerobic | GasPak Jar |
| cold loving bacteria; 5℃ - 20℃ | psychrophile |
| moderate/warm loving bacteria; 20℃ - 45℃; 2 common optimal temps: 25℃/Room temperature, 37℃/Body temperature | mesophile |
| hot loving bacteria; 45℃ - 55℃ | thermophile |
| a type of mesophile that can grow at 0C; range from about 0C-30C | psychrotroph |
| What is the genus of the thermophile we grew in class? | Bacillus (stereothermophilus) |
| What bacteria Genus makes a red pigment at 25C? | Serratia (marcescens) |
| temp: minimum, optimum, and maximum temp requirements are also known as? | cardinal temperatures |
| solid growth on plate | lawn |
| Quantitative plate count: formula for determining bacterial count | # colonies x dilution factor divided by volume plated = colonies or cells/mL |
| What does PCR stand for? | polymerase chain reaction |
| What is PCR used for? | DNA replication in a test tube; replicate ocean bacteria, trace tainted produce, trace outbreaks in healthcare settings |
| any replication done with heat; a specialized machine used to rapidly heat and cool samples in PCR | thermocycler |
| PCR step/cycle: heat to "unzip"/melt target DNA; disrupts the hydrogen bonds b/w the two complementary DNA strands and cause their seperation | denaturation |
| PCR step/cycle: reaction mixture cooled which allows the primers to base pair with the target DNA sequence | annealing (sticking) |
| PCR step/cycle: temp raised which causes polymerase to add nucleotides to synthesize the new complementary DNA strands | extension |
| What is agarose gel electrophoresis used for? | visualize and measure DNA |
| used to visualize DNA properties under the UV light | ethidium bromide card |
| process of using electricity to move something; to visualize and measure DNA | agarose gel electrophoresis |
| name of the piece of equipment that the ethidium bromide is put into | gel electrophoresis apparatus (or gel box) |
| first lane on ethidium bromide card | control ladder |
| PCR test: what is the white ball with TAq Polymerase made of? | magnesium chloride |
| stopping/slowing growth | ___static |
| killing the microbe | ___cidal |
| controlling microbes on a non-living surface (fomite) | disinfectant |
| controlling microbial growth on a living surface | antiseptic |
| antimicrobial susceptibility test; used for measuring effectiveness of antimicrobials against pathogenic microbes | Kirby-Bauer method (aka Disc Diffusion method) |
| type of chemical that works by denaturing the proteins and breaking the cell membranes--> cell death | phenols (Lysol) |
| chemical that works by oxidizing agents that work by denaturing proteins or by forming oxidizing agents | halogens (iodine) |
| chemical that works by dissolving lipids in cell membrane and by denaturing proteins; kill gram - | alcohol (isopropol alcohol) |
| work by breaking down the bacterial cell membrane (since it combines with a phospholipid) and denatures the proteins | quaternary ammonium compounds (Cepacol) |
| completely clear zone around disc in Kirby-Bauer method; the "kill zone" | zone of inhibition |
| qualitative vs quantitative? yes or no result | qualitative |
| qualitative vs quantitative? goes beyond yes or no result, i.e. effectiveness of ATB against bacteria, measuring the zone of inhibition | quantitative |
| against life; many are produced by living organisms | antibiotic |
| unit of measurement for Kirby-Bauer technique; measuring what? | mm; diameter of zone of inhibition |
| the ability of a microbe to withstand the effects of an antibiotic | resistance |
| microbe somewhat sensitive to the antibiotic | intermediate |
| microbe is killed by antibiotic | sensitive |
| Kirby-Bauer method result: chemical testing--> qualitative or quantitative? | qualitative (did it work--yes or no?) |
| Kirby-Bauer method result: ATB sensitivity testing--> qualitative or quantitative? | quantitative (effectiveness? numerical data based on measuring zone of inhibition) |
| Can you 'eyeball' ATB sensitivity testing result? | no, need to measure diameter of zone of inhibition then use table/chart to determine result (for correct ATB) |
| Which microbe digests blood? has it's own special plate---name of plate? Looking for what? | S. pyogenes; BAP; look for hemolysis |
| taking two Ts and binding/gluing them together; exposure to UV causes _____ to lock together therefore not allowing the proper base pairing to occur--->effects bacterial replication and can cause mutation in cells | thymine dimer |
| white light (room light) causes ____?; reverses mutation (separates/unlocks the locked dimer) | photoreactivation |
| time for UV to kill Serratia marcescens | 1-minute |
| UV light testing: colonies within UV-exposed area begin to develop when exposed to white light (room light); light-activated DNA repair enzyme | photoreactivation photolyase |
| a method of separating out bacteria to be able to pick out individual colonies, therefore each separate colony is a small pure culture | streak plate method |
| Streak Plate method steps | flame inoculating loop and cool for all 3 steps (1st time--gently shake, 2nd/3rd cool loop in side of plate), tight lines in 1st section, looser lines each time in 2nd and 3rd sections, initial swipe in 2 and 3 is taken from previous section |
| basic growth media | TSA (Tryptic Soy Agar) |
| differentiates hemolytic types, indicator-blood, alpha/beta/gamma | TSA (Tryptic Soy Agar) + 5% Sheep's blood (BAP) |
| media type: differentiates fermentation types; indicator is ____ ____ | PR Sugar, Phenol Red |
| differentiates O2 requirements category, indicator ______ | Thioglycollate |
| selects for halophiles (staph species), inhibitor-high salt concentration, differentiates-mannose fermentors (b/w staph species), indicator-phenol red | MSA (Mannitol Salt Agar) |
| MSA media turns yellow | S. aureus (mannose fermenter) |
| MSA media with no color change | S. epidermititis (non-fermenter) |
| selects for G+, inhibitor- ____, differentiates-hemolytic types, indicator-blood | PEA-B (Phenyl Ethyl Alcohol) |
| selects for G-, inhibitor-bile salts, differentiates-lactose fermentors (E. coli), indicator-neutral red; lactose fermentors (E. coli) turn magenta, non-lactose fermentors--no color change | MacConkey |
| selects for G-, inhibitor-dye, differentiates-lactose fermentors, indicator-dye; lactose fermentors (E. coli) turn metallic green, non-fermentors--no color change | EMB (Eosin Methylene Blue) |
| means sulfur group somewhere | thio |
| Kirby-Bauer method steps | rub microbe all over TSA plate, place infused discs (chemical or ATB discs) on plate, check for zone of inhibition |
| Which media(s) are differential only? | TSA + 5% sheeps blood, Thioglycollate |
| Which media(s) are selective and differential? | MSA, PEA-B, MacConkey, EMB |
| type of media that contains an inhibitor that inhibits the growth of everything but what you're looking for | selective media |
| media that contains an indicator that indicates difference b/w microbes growing on the media | differential media |
| crystallized form of something; high-osmotic pressure (ability to draw fluids) | a salt |
| aka fast test; looking for antibody immunity | ELISSA |
| What does ELISSA stand for? | Enzyme Linked Immuno Absorbance Assay |
| ELISSA test: looking for antigen in pt's blood | direct |
| ELISSA test: looking for lab-created antigen | indirect |
| results of ELISSA test | positive, weak positive, or negative |
| Do you need exact timing for ELISSA test? | yes--can get false results d/t color sticking more and more in sample |
| quality control of ELISSA test | at least 3 replicates for each specimen |
| Why would ELISSA results be weak positive instead of full positive? | time of exposure, how big of dose, previous exposure (titers), how sick host was |
| dye used in ELISSA test | chromogen |
Created by:
nurse savage
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