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MyMicro Final Review
| Question | Answer |
|---|---|
| Where are obligate anaerobes commonly found? | Lower intestine |
| If oxygen is present, which type of metabolism will a facultative anaerobe use? And if oxygen is absent? | Aerobic respiration; fermentation or anaerobic respiration |
| Which type(s) of metabolism can obligate anaerobes use? | Fermentation or anaerobic respiration |
| T/F Many microaerophiles are canophiles. | True |
| Which type of bacteria can live in an oxygen atmosphere but cannot use oxygen for its growth? | Aerotolerant anaerobe |
| Which type of bacteria can grow with or without oxygen? | Facultative anaerobe |
| Which type of bacteria require increased CO2? | Canophiles |
| Which type of bacteria can be destroyed by as little as 10 minutes exposure to oxygen? | Obligate anaerobe |
| Which type of bacteria need oxygen to grow & survive, but only at levels that are lower than atmospheric? | Microaerophilic bacteria |
| When the sodium borohydride and sodium bicarbonate of a Gas-Pak combine with water, what chemicals are produced? | Hydrogen gas and carbon dioxide |
| Why does a Gas-Pak need to produce hydrogen gas? | To combine with free oxygen to produce water |
| Why does a Gas-Pak need to produce CO2? | To replace the oxygen |
| What is held in the mesh basket on the Gas-Pak lid and why is it needed? | Palladium; needed to catalyze the reaction |
| What type of broth is thioglycollate broth? Enrichment, enriched, differentiation, selective | enriched & differentiation |
| What pH indicator is used in thioglycollate broth? | phenol red |
| In thioglycollate broth, what color indicates ≥ 3% CO2? | yellow |
| In thioglycollate broth, what color indicates presence of oxygen? | pink |
| What is the purpose of steaming or briefly boiling a tube of pink thioglycollate broth? | To release the oxygen gas and return the medium to an anaerobic state |
| T/F When working with anaerobes, work slowly and carefully. | False; work quickly to minimize introduction of air |
| When do bacteria form endospores? | when stressed, sub-lethally injured, placed in danger |
| Which of the following does NOT describe an endospore? | Dormant, Gram positive, vegetative, tough |
| The most common endospore are produced by which 2 genera? | Clostridium and Bacillus |
| An endospore has a thick wall that encloses its _____ and part of its _____. | DNA and cytoplasm |
| When does an endospore germinate into a vegetative cells | When the threat has subsided or the bacterium is killed |
| Which of the following can kill an endospore? UV, Gamma radiation, dessication, lysozyme, starvation, extreme temperature, chemical disinfection, all of the above, none of the above | none of the above |
| Where are endospores commonly found? | in the soil |
| What is an endospore’s outermost layer called? | Exosporium |
| What makes up the cortex of an endospore? | Peptidoglycan |
| The core of an endospore is also called a ______. | protoplast |
| What does an endospore’s germ cell wall and plasma membrane do? | Protect the core |
| Why is an endospore’s DNA encased in protein? | to protect it from UV radiation and heat |
| Calcium dipicolinate makes up what percentage of an endospore’s dry weight? | 15% |
| Calcium dipicolinate is found in the ___ of the endospore. | core |
| Calcium dipicolinate functions include: ___ stabilization, resistance to ____ and resistance to ____ agents. | DNA; heat; oxidizing |
| Endospores can be produced by forcing ____ of nutrients or providing the medium with ____ nutrients. | depletion; minimal |
| How can you harvest endospores in a broth culture? | centrifuge the broth on low speed |
| How can you havest endospores on an agar plate? | surface scraping followed by coarse filtration |
| The complete destruction of all microbial cells present | sterilization |
| In heat sterilization D-values indicate the amount of time required for a ____reduction in the population density at a given temperature. | ten-fold |
| D-value and temperature have a(n) ____ relationship | exponential |
| Which is an easier way to characterize heat sensitivity: D-values or Thermal Death Time? | thermal death time |
| The time at which cells in a suspension are killed at a given temperature | thermal death time |
| On semilog paper, thermal death time vs. temperature shows what shaped line? | straight |
| High concentrations of sugars, proteins, and fats usually ___ the resistance of organisms to heat | increase |
| High concentrations of ___ may increase or decrease resistance to heat. | salt |
| Microbial death is more rapid in ____ pH values. | acidic |
| T/F Dry cells and spores are more heat resistant than moist ones but require higher temps and longer time to sterilize | T |
| What is the most heat resistant structure known and what determines its heat resistance? | bacterial endospores; water in the protoplast |
| What moves freely in and out of spores? | water |
| What temperature, pressure & time are required to destroy spores? | 121°C, 15 lbs/in2, 10-15 min |
| What are the three major filter types and which is the most common? | Depth, Membrane, Nucleopore ; Membrane most common |
| In which type of filter sterilization do particles get trapped in the tortuous paths created by the fibers? Depth | |
| In which type of filter sterilization are thin polycarbonate films treated with nuclear radiation and then etched with a chemical? | nucleopore |
| Which type of filter acts like a sieve, trapping many particles on the surface and which is a true sieve? | acts like sieve – Membrane; true sieve – nucleopore |
| Which type of filter are 80-85% open space to provide a high fluid flow rate? Membrane | |
| Which type of filter is used in scanning electron microscopy? | nucleopore |
| Which antimicrobial agent lyses cells? bacteriolytic | |
| Which antimicrobial agent binds tightly to their cellular targets and are not released by dilution? | Bactericidal |
| Which antimicrobial agent binds ribosomes to inhibit protein synthesis and growth? | bacteriostatic |
| Which antimicrobial agent both inhibits growth and induces killing without rupturing cells? | Bactericidal |
| What does MIC stand for? | Minimum Inhibitory Concentration |
| In which measurement of antimicrobial activity of a chemical are serial dilutions performed? | Minimum Inhibitory Concentration |
| In which measurement of antimicrobial activity of a chemical are filter papers with known amounts of antimicrobial agent placed on agar plates? | Agar diffusion method |
| In which measurement of antimicrobial activity of a chemical can the Zone of Inhibition be measured? | agar diffusion method |
| In UV sterilization, what is required to prevent harm to untargeted plants, animals, and microorganisms? | special containment or chambers |
| UV sterilization works by damaging ___. | DNA |
| Which UV band is 100-280nm? | UVC |
| Which UV band is 315-400nm? | UVA |
| Which UV band is 280-315nm? | UVB |
| What is the most effective biocidal wavelength? | 254nm |
| UVC is also called ____ UV. | far |
| T/F The most effective biocidal lamps use single wavelength bulbs. | False |
| What does NAG stand for? | N-acetyl glucosamine |
| What does NAM stand for? | N-acetyl muramic acid |
| How much ATP is lost as heat during aerobic respiration? What % of the energy produced is this? | 19 ATP and 50% |
| What is the difference between anaerobic and aerobic respiration? | Aerobic respiration requires oxygen as an inorganic electron acceptor Anaerobic respiration uses other chemicals for respiration, such as hydrogen sulfide |
| Acetyl Co-A and oxalacetate bind to form what? | Citrate |
| The substance oxidized during oxidation reduction is known as what? The substance reduced? | Electron donor; electron acceptor |
| In what growth phase are secondary metabolites produced? | stationary |
| What are the basic chemical substances required by cells that come from the environment? | nutrients |
| How can you prevent a lag phase from occurring? | Transfer cells from a culture in exponential phase into the same media under the same conditions |
| Why do many oxidation reduction reactions NOT involve molecular oxygen (02)? | Because 02 is a final electron acceptor and the transfer of hydrogen atoms/electron is more important |
| Define a viable cell. | Cells that are able to divide and form offspring |
| What does ATP stand for and where does it store energy? | Adenosine; Energy is stored in the phosphate bonds |
| What triggers stationary phase in a microbial growth cycle? | Essential nutrients are used up or waste products from the organism builds up to an inhibitory level |
| What special enzyme is used to catalyze reversible reactions between ATP, ADP, and inorganic phosphate? | ATPase |
| With the exception of molybdenum and tungsten, the elements found in all living organisms are below what number on the periodic table? | 30 |
| What do all organisms require to grow? | Macro- and micronutrients |
| Why doesn’t a Gram negative cell wall stay purple after washing with decolorizing solution? | The outer membrane gets washed away. |
| How long do you de-stain a Gram stain? | Until the color stops running |
| When does respiration rather than fermentation occur? | Respiration if the microorganism has the tools to deal with oxygen and then when oxygen is available Fermentation occurs when no oxygen is available |
| What is peptidoglycan made of? | Units of NAG and NAM connected by β 1,4 linkages |
| What method of energy formation in anaerobes is related to the ability or the organism to infect humans? | Fermentation |
| What are the final products of aerobic respiration? | Water and CO2 |
| Who created swan-necked flasks to allow air circulation? | Louis Pasteur |
| Who supplied a means of demonstrating that specific organisms cause specific diseases? | Robert Koch |
| Who described fruiting bodies on molds? | Robert Hooke |
| What characteristics of microorganisms distinguishes them from plant and animal cells? | Microorganisms exist as a single cell or cell cluster. Plant and animal cells cannot live alone. |
| The first artificial, semi-solid media was made by heating what component with blood serum? | Gelatin |
| Which four atoms make up the weight of a cell? | Carbon, Oxygen, Hydrogen, Nitrogen |
| Where do cells obtain required nitrogen? | From the breakdown of dead organisms |
| List 4 macronutrients | Carbon, nitrogen, phospohorus, magnesium, sulfur, potassium |
| Which macronutrient is important in protein synthesis? | potassium |
| Which macronutrient stabilizes ribosomes? | magnesium |
| Which macronutrient is in cysteine and methionine? | sulfur |
| Explain the two classes of nutrients. | Micronutrients – Required in small amounts ; Macronutrients – Required in large amounts |
| Which class of culture media has precise amounts of each component? | Chemically defined or synthetic |
| Which class of culture media a crude digest of substances like casein, yeast, beef, or soy | Undefined or complex |
| List five major characteristics to consider a cell as living. | Self feeding Self replicating Differentiation Chemical signaling Evolution |
| What are the major components of cytoplasm? | Water Macromolecules Ribosomes Small organic molecules Various inorganic ions |
| What are some of the most significant differnces between prokaryotic and eukaryotic cells? | Size, cell wall, nuclear structure |
| In anaerobic respiration, what type of electron acceptors are used? | Inorganic |
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