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35 Cards in this Set
- Front
- Back
- 3rd side (hint)
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MC imagine you did your Gram stain last week and got all pink cells after staining your mixed culture of Gram + and - cells. The most likely mistake that you made was that you: |
a. left the safranin on the cells too long b. added too much iodine c. applied crystal violet too late in the process d. washed off all the weakly attached gram + cells e. added alcohol for too long |
e. added alcohol for too long alcohol decolorizes the CV stain from G- bacteria so that the G- can pick up the safranin in next step. when left for too long = everything looks G- |
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describe quadrant streak plating of mixed culture and its expected growth. |
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MC when doing MPN analysis, scientists... |
a. examine a water sample for the presence of somatic coliphages b. put a water sample under a microscope and count the # of cells they see. c. look for bacterial growth in broth tubes after water sample is inoculated into them d. apply a chemical dye to a water sample & then look for a specific color change e. pass a large volume of water through a filter & then attach it to an agar dish |
c. look for bacterial growth in broth tubes after water sample is inoculated into them most probable number analysis; coliform selecting broth in tubes is inoculated to measure growth patterns in stock solution, 1:10, and 1:100 dilutions. Theoretically, the ratio should be even (4:2:1) |
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SA describe the concept of an indicator species in terms of what it is, and why it's used in water testing. |
Indicator species - like coliform bact. and phages - are used to determine the general presence of other pathogens possibly in the water that would indicate the sample needs to undergo further testing. |
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MC all of the following are true considering food borne microbes except: |
a. some food borne bact. secrete toxins within the intestine b. many foods get contaminated due to pathogens in the soil c. food must be free of microbes to be approved by the FDA. d. some bact. ingested becomes a part of our normal flora e. some food borne pathogens produce little visible change to the food they contaminate |
c. food must be free from microbes in order to be approved by the FDA many food/drinks are naturally contaminated with microbes; often from the soil |
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SA describe the concept of MPN analysis for quantitating fecal coliforms; give a basic description of the experiment, the data produced, and interpretation. |
- sample is diluted 1:10, 1:100 - orig. sample + dilutions inoculated into 5 tubes each w/ broths that favor coliform growth - more dilute = less growth; observe pattern of ratios - can use tables to estimate conc. of coliform bact. in orig. sample |
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MC when growing up coliophage last week, you purposely added E.coli at some point. what was the purpose of this step? |
a. to conjugate w/ other bact. in sample b. to increase # of coliophage in sample. c. to neutralize naturally alkaline waters in lakes/streams d. to serve as a control when sample is plated on EMB agar e. to kill off any interfering bact. in water sample |
b. to increase # of coliophage in sample. coliphages infect coliform bact. - by adding more coliform bact. to the water sample, able to determine how many phages are in sample. |
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SA describe 3 major ways of controlling microbial growth in food. |
temp: refrigeration/freezing produces low temps that slow growth of nearly all pathogens cooking: high temps denature proteins, destroy membranes + DNA preservatives: low osmolarity via high sugar/salt inhibits bact. growth |
T C P |
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MC during alcohol fermentation... |
a. only about 16 ATP are produced b. pyruvate is converted to acetaldehyde c. microbes mist be grown in a low pH environment d. two simple alcohols are combined to produce one e. sugars are converted into ethanol using four different enzymes |
b. pyruvate is converted to acetaldehyde |
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MC what was the purpose of adding lysozyme to the probiotic suspension in last week's experiment? |
a. separates bact. from non-active ingredients of the pill b. activates the bact. in pill c. triggers bact. to secrete digestive enzymes d. prevents the lysosome from destroying bact. e. mimics host defenses in the saliva |
e. mimics host defenses in the saliva |
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describe the line graph that would depict the relationship between sugar concentration and bacterial growth in relation to the raw chicken mixture experiment. |
the graph will have a bell curve the bact. will grow happily until it can't continue to grow in high sugar concentrations because of the inhibition from low osmolarity. |
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MC all of the following are true concerning tests used to identify clinical pathogens except: |
a. some detect unique enzymes made by pathogen b. some viral genomes can be detected using fluorescent probes c. some forms of PCR do not require the polymerase enzyme d. some test for antibodies rather than pathogens themselves e. some tests can be positive in the absence of the pathogen. |
c. some forms of PCR do not require the polymerase enzyme PCR literally stands for polymerase chain reaction |
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SA describe the three major steps of PCR cycle. |
- denaturation of template DNA stand: the 2 strands that make up DNA must be separated using 95 C for 1-1.5 min - annealing of primers to strands: primers will anneal to complimentary regions of template strands at 55-65 C for 1 min - extension of primers by Taq polymerase: primers direct Taq to where to begin creating new DNA at 72 C for 1 min EXPONENTIAL AMPLIFICATION |
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MC failing to add ATL buffer during DNA purification procedure last week would cause which of the following problems? |
a. DNA remains stuck in spin column b. DNA is stuck inside cells c. DNA is contaminated w. lipids d. DNA that misfolded e. DNA is contaminated w. proteins |
b. DNA is stuck inside cells |
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SA imagine you did a PCR reaction last week and it didn't work. what are three things you could have forgotten to add to the tube that would result in no product? |
- if there weren't any added primers, the product bands can't actually test positive for anything - if Taq if forgotten, bonds can't form and no new DNA is created - if no buffer is added, PCR won't stay at proper pH = won't work or form a gel |
P T B |
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MC if you start with 4 copies of DNA and perform 3 rounds of PCR, how many copies of DNA will you have at the end? |
a. 4 b. 12 c. 24 d. 32 e. 64 |
d. 32 exponential 4x2 = 8x2 = 16x2 = 32 |
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SA what are the two functions of loading dye used in gel electrophoresis? |
- increases density of mixture so it sinks into the well - allows us to observe the progress of electrophoresis DOES NOT STAIN ANYTHING |
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MC all are true concerning agarose gel electrophoresis except... |
a. loading dye does not stain the DNA b. larger DNA molecules move further through the gel than smaller DNAs c. Gels must be run in buffered solution d. DNA is visualized only under UV light e. one must always run DNA towards the positive electrode |
b. larger DNA molecules move further through the gel than smaller DNAs |
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SA imagine you run a gel electrophoresis and get a troubling result; three of the four lanes have a band. what went wrong + why vs what you expected to see. |
the same enzyme would have had to be accidentally added to three of the four lanes from poor technique only one of the four lanes should be yielding a positive result |
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MC all the following are true concerning mechanisms of antibiotic resistance except sometimes.... |
a. antibiotic is blocked from getting into cell b. cellular target of antibiotic is mutated c. bacterium can chemically alter the antibiotic d. bacterium will pump antibiotic out of cell. |
e. bacterium will bring antibiotic into their lysosomes. bacteria don't have lysosomes, they're prokaryotic |
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SA describe 3 ways in which humans have exacerbated the antibiotic resistance problem. |
- agricultural industry: mass inoculation of livestock with antibiotics that excrete into soil/water - overprescription: prescribing broad spectrum antibiotics for everything + viral infections - patient mistakes: taking old antibiotics after expiration/degradation, stops taking antibiotics when they feel better and don't get full treatment |
AI O PM |
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MC during alcohol fermentation..... |
a. only about 16 ATP is made b. pyruvate is converted into acetaldehyde c. microbes must be grown in low pH environments d. two simple alcohols are combined to produce one e. sugars are converted into ethanol using four different enzymes |
b. pyruvate is converted into acetaldehyde that's the alcohol part |
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SA describe the process of feedback inhibition as it pertains to alcohol fermentation |
the inhibition of enzymes contributing to fermentation because of the accumulation of high concentrations of alcohol products |
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MC all the following are statements are true concerning antibiotics and antibiotic resistance except: |
a. some antibiotics target bacterial ribosomes b. some antibiotic resistance genes found on plasmids c. some bact. become resistant by mutating the target of the antibiotic d. some antibiotics act as nucleases against bacterial mRNA e. some bacteria pump antibiotics back out of their cells |
d. some antibiotics act as nucleases against bacterial mRNA |
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MC all of the terms can be used to describe actinomycetes except: |
a. prokaryotic b. basidiospore c. filamentous d. antibiotic e. decomposition |
b. basidiospore |
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SA how did you isolate soil fungi away from bacteria and how did you isolate endospores away from other bacteria? give two answers. |
endospores: the culture was boiled in hot water to kill any bact. or fungi in the sample; then plated on TSA to allow spores to germinate soil fungi: grow selectively on Sabouraud Dextrose Agar + Abics |
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SA name two ways to test nutrient cycling in soil microbes. |
- decomposition of cellulose paper to utilize as a carbon source - nitrification of an ammonia broth to utilize as a nitrogen source |
decomp + nitrification |
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SA describe bact. endospores in terms of what triggers them to form and their metabolic activity. |
triggered to form during environmental instability (lack of nutrients, space). no metabolic activity present because the spore is formed as a DNA escape pod from the original cell; once conditions are favorable, germination will begin |
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SA what is meant by microbial bioremediation |
the use of microbes to clean up or dispose of human waste like industrial heavy metals and other pollutants by converting them into usable macromolecules |
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SA isolate a toxic organic compoinds called loomisol that is utilized during process of making blue jeans. describe process by which you'd isolate the species. |
- get a soil or water sample from an environment (textile factory) where loomisol is present - dilute sample to 10 -4/-5, plate on loomisol laced agar to select for strains that can degrade it |
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SA what is Rid X and what does it do? |
an additive solution of enzymes and billions of bacteria for waste containment that uses the degradative enzymes made by microbes to destroy harmful waste materials |
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MC which of the following types of agars is the most useful when trying to isolate microbes that destroy long chain hydrocarbons? |
a. TSA b. mannitol salt agar c. sabaroud dextrose agar d. minimal media agar e. FC agar |
d. minimal media agar minimal media puts a selective pressure on the microbes plated, allowing for only hydrocarbon utilizing bact. to grow |
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SA the plate with the highest copper concentration still has a few colonies on it. your goal: a bug that can do broad clean up of heavy metals in soil. three things you'd do next? |
- increase concentration of the metal in the agar until it's as close as possible to an accidental pollutant's conc. - make plates with other common pollutant heavy metals and begin to expose the bug to them at various concentrations - make broth cultures of heavy metals to see if the microbe could accomplish clean up in a different substrate |
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MC which of the following is not a characteristic of biofilm growth? |
a. organsims grow as free floating aggregates b. cells engage in quorum sensing c. produce polysaccharide matrix d. exhibit increased antibiotic resistance e. can contain multiple species |
a. organisms grow as free floating aggregates |
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SA two factors that affect the attachment and growth of biofilms. |
nutrient availability: the biofilm can only grow so large before it exponetially eats through all surrounding nutrients competition for space: biofilms aren't thing attaching to substrates + if there's physically nowhere to fit, growth will be impedded |
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