Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
microbiology jc
microbiology test 2 chapter 4
| Question | Answer |
|---|---|
| Prokaryotic cells divide by: | binary fission |
| Why is binary fission a simpler and quicker way to reproduce? | no organelles, asexual, one cell divides into two daughter cells |
| What is the time it takes for a population to double in number called? | generation time |
| When is exponential growth a positive? | great for experiments and to produce medications such as insulin for diabetics |
| When is exponential growth a negative? | food borne pathogens |
| What are the five stages of the growth curve? | lag phase, exponential or log phase, stationary phase, death phase, and phase of prolonged decline |
| At what phase of growth are microbes most sensitive to antibiotics? | exponential or log phase |
| What happens during the lag phase? | the cells are introduced to the environment, the number of cells does not increase, the cells begin synthesizing enzymes required for growth (the cells are in a vegetative state because they are not metabolically inert) |
| What happens during the exponential/log phase? | cells divide at a constant rate and this is when the generation time is measured |
| At which phase of growth do endospores start to form? | the end of the log/exponential phase |
| What happens during the stationary phase? | nutrient levels are too low to sustain growth and the total number of cells remains constant. A few cells are reproducing as the same number are dyeing |
| What happens during the death phase? | total number of viable cells decrease (die) at a constant rate (exponentially but slower) |
| What happens during the phase of prolonged decline? | some fraction may survive. They adapt to tolerate the worsened conditions |
| What does it mean to say that prokaryotes are ubiquitous? | inhabit nearly all environments |
| What are the major conditions that influence growth? | temperature, pH, water availability, atmosphere (levels of oxygen) |
| Optimum growth usually occurs at what temp: | close to the upper end of the range for that species of microbe |
| Psychrophile: | -5o to 15o C (arctic or Antarctic regions) |
| Psychrotroph: | 20o to 30o C (cause food spoilage in refrigerator) |
| Mesophile: | 25o to 45o C (body temp range-pathogens) |
| Thermophiles: | 45o to 70o C (hot) |
| Will refrigeration kill microbes? | no, but will slow them down |
| What range of pH do most bacteria maintain internally? | typically near neutral |
| Neutrophiles: | pH range 5-8 and have a pH optimum near neutral (pH 7) Most microbes are neutrophiles |
| Acidophiles: | grow optimally at a pH below 5.5 |
| Alkaliphiles: | grow optimally at a pH above 8.5 |
| How does H. pylori survive in the stomach? | it produces urease to split urea into CO2 and ammonia which neutralized the area around it so it can survive the stomach acid |
| When water leaves cells, what happens? | it interferes with normal metabolic processes |
| What do dissolved salts and sugars do to cells? | make water unavailable to the cell, causing cells to slow their growth or die |
| Microbes that tolerate high concentrations of salt: | halotolerant |
| Microbes that require high levels of sodium chloride: | halophiles |
| When organisms us oxygen in aerobic respiration, what harmful derivatives are formed as by-products? | reactive oxygen species (ROS) (hydrogen peroxide and superoxide) |
| What is superoxide dismutase? | an enzyme produced to inactivate superoxide by converting it to oxygen and hydrogen peroxide |
| What is catalase? | an enzyme produced to convert hydrogen peroxide into oxygen and water. |
| Obligate aerobes: | need oxygen for growth, produces superoxide dismutase and catalase |
| Obligate anaerobes: | cannot multiply in the presence of oxygen, does not produce superoxide dismutase and catalase |
| Facultative anaerobes: | grow best in presence of oxygen but can also grow in the absence of oxygen, produces superoxide dismutase and catalase |
| Microaerophilic: | require small amounts of oxygen for growth, produces some superoxide dismutase and catalase |
| Aerotolerant anaerobes: | don’t use oxygen to grow but being in presence of oxygen isn’t going to kill or hinder them, produces superoxide dismutase but not catalase |
| A species grows must rapidly at its ____________ growth temperature: | optimal |
| During which phase of growth does the number of new cells balance the number of declining cells? | stationary phase |
| The optimum temperature of a psychrophile would be higher, lower, or the same as a thermophile? | lower |
| Microorganisms which prefer hot environments (optimum temperature 45o to 70o C) are termed: | thermophiles |
| When bacteria are transferred from one environment to a new growth medium, which phase of growth is first observed? | lag |
| A _________curve is a graphical representation of the change in population size over time. | growth |
| The enzyme ___________ converts hydrogen peroxide formed during aerobic respiration to water and oxygen. | catalase |
| What name is used to describe a microbe that prefers environments that have a pH greater than 7? | alkaliphile |
| Why are species of Staphylococcus halotolerant? | They have evolved to survive in dry, salty environments such as human skin. |
| If the solute concentration is higher outside the cell than inside the cell, water will diffuse out due to osmosis. This will result in: | plasmolysis |
| True or false:In a growth curve, cell numbers increase exponentially during the log phase and decrease exponentially during the death phase | True |
| What is an organism that prefers acid pH (below 7) called? | acidophile |
| What name is given to microbes that prefer environments near or at a pH of 7? | Neutrophile |
| What phase describes the initial phase after bacterial cells are placed into a new environment and are gearing up for cell division, but their numbers have not yet increased? | lag phase |
| With regard to their temperature requirements, medically important microorganisms are typically __________ because they have evolved to thrive in or on the human body.: | mesophile |
| Which term refers to bacteria that require high concentrations of salt? | halophile |
| What is an aerobe that requires oxygen at a concentration less than that in the atmosphere? | microaerophile |
| Removal of all microbes: | sterilization |
| Reduction of the number of microorganisms: | disinfection |
| Something used on inanimate objects to reduce the number of microorganisms: | disinfectant |
| Something used on living tissue to reduce microorganisms: | antiseptics |
| Brief heating to reduce number of spoilage organisms and destroy pathogens but is not a sterilization method: | pasteurization |
| Process of delaying spoilage of foods and other perishable products: | preservation |
| Why is it important to minimize the number of microorganisms in the healthcare setting? | because of the danger of healthcare associated infections |
| Why is it possible to get a healthcare associated infection? | invasive procedures, compromised immune systems, more infectious diseases found there |
| Destruction of Endospores: | will take extreme heat or chemicals to destroy |
| Destruction of Protozoan cysts: | resistant to any disinfectant and excreted in feces, cause diarrheal diseases, easily destroyed by boiling |
| Destruction of Mycobacterium species: | waxy cell wall makes them resistant to many chemicals |
| Destruction of Pseudomonas species: | leaves green sheen over burn wounds, can actually grow in some disinfectants and is resistant to others |
| Destruction of Naked virus: | doesn’t have a lipid envelope which makes it more resistant to disinfectants |
| The time it takes for heat or chemicals to kill a microbial population is dictated in part by: | the number of cells present |
| What will minimize the amount of time necessary to sterilize or disinfect a product? | removing organisms by washing or scrubbing |
| Why is heat treatment one of the most useful methods of microbial control? | because it is reliable, safe, relatively fast and inexpensive, and does not introduce potentially toxic substances into materials. |
| How does moist heat destroy microbes? | by irreversibly denaturing their proteins |
| Examples of moist heat: | boiling, pasteurization, pressurized steam |
| Boiling: | destroys most microorganisms and viruses but endospores can survive |
| Pasteurization: | destroys pathogens, spoilage organisms |
| Autoclave: | used to sterilize using pressurized steam |
| Temp and pressure sterilization typically takes place in an autoclave: | 121oC & 15 psi in 15 minutes |
| What are the signs and symptoms of botulism and how long does it take to begin? | 12-36 hours after eating toxin contaminated food, dizziness, dry mouth, blurred or double vision, abd pain, nausea, vomiting, diarrhea or constipation, progressive paralysis of all voluntary muscles |
| What is the causative agent of botulism? | Clostridium botulinum a gram-positive, spore forming rod that produces a neurotoxin (works on acetylcholine) |
| Pathogenesis of botulism: | due to vegetative cells releasing the toxin, toxin passes through stomach and is absorbed in the small intestine. Can circulate in the bloodstream |
| Treatment and prevention of botulism: | IV anti-toxin, only neutralizes toxin in blood. Affected nerves slowly recover. Can take weeks or months and respiratory support is needed. Prevention: proper canning |
| What is a method of dry heat sterilization that is used on medical waste, animal carcass, and in the lab: | Incineration |
| What type of radiation has enough energy to remove electrons from atoms, thereby destroying DNA and damaging cytoplasmic membranes? | ionizing |
| A sterile object is free of: | all viable microorganisms and viruses |
| ________ is a brief heat treatment to destroy disease-causing organisms in foods and beverages. | Pasteurization |
| Preventing contamination in the microbiology lab requires the stringent practice of: | aseptic technique |
| A concentrated culture will take __________ time to kill than a dilute culture of the same organism. | more |
| When using chemical disinfectants, it is important to realize that temperature and _________ influence microbial death rates significantly. | pH |
| What is a chamber that allows the use of steam under pressure to sterilize materials? | autoclave |
| What destroys microbes by subjecting them to extremes of dry heat, reducing them to ashes? | incineration |
| These infectious proteins are very difficult to destroy: | Prions |
| ________________radiation in the 220 to 300 nanometer range destroys microbes by damaging their DNA. | Ultraviolet |
| Which microbial agent is the most resistant to chemical control methods? | bacterial endospores |
| Paper-thin membrane filters called _____________contain pore sizes so small they will trap microbes from liquids as they pass through. | microfilters |
| Soap generally does not destroy most microbes but it aids in their: | removal |
| Water treatment facilities work to ensure that these are not found in drinking water: | pathogenic microbes |
| High pressure (130,000 psi) is thought to kill microbes by altering: | their cell membranes and proteins |
| When filtering fluids, ________ trap material within thick, porous filtration material such as cellulose fibers.: | depth filters |
| Removing or destroying all microorganisms and viruses from an object renders the object: | sterile |
| __________are chemicals used to decrease the number of microbes on living tissue. | antiseptics |
| Eliminating most or all pathogens in or on a material: | disinfection |
| Moist heat requires __________ exposure times and lower temperatures than dry heat.: | shorter |
| Exposing proteins to high heat may cause protein: | denaturation |
| What kind of radiation can remove electrons from atoms? | ionizing |
| What kind of rays are ionizing radiation and used to sterilize heat-sensitive materials after packaging? | gamma rays and xrays |
| What kind of radiation destroys microbes directly and is used to destroy microbes in air, water and on surfaces? | ultraviolet radiation |
| Ionizing radiation harms cells by destroying ___________and damaging____________. | DNA, cytoplasmic membranes |
| The sum of all the reactions happening in an organism is: | metabolism |
| What two fundamental tasks must cells accomplish to grow? | synthesize new components for repair and reproduction and harvest energy for survival |
| What are the two components of metabolism? | anabolism and catabolism |
| Reactions produce energy from the breakdown of larger molecules is: | catabolism |
| Reactions involved in the synthesis of cell components is called: | anabolism |
| What is the energy currency of the cell? | ATP (adenosine triphosphate) |
| ATP becomes what when it loses a phosphorous? | ADP |
| Exergonic reactions: | give off energy |
| Endergonic reactions: | take energy to make |
| What three things happen in the breakdown of ATP? | a phosphate is removed, ATP becomes ADP, energy is released |
| What is the role of enzymes in metabolism? | speed up reactions |
| How do enzymes catalyze reactions? | lowering activation energy |
| What assist some enzymes (lock and key)? | cofactors |
| What substances are cofactors? | magnesium, zinc, copper, other trace elements |
| What are FAD and NAD? | electron carriers |
| What environmental factors influence enzyme activity? | temp, pH, salt concentration |
| How do non-competitive inhibitors work? | attach to an allosteric site on the enzyme which changes the shape of the active site so a substrate cannot bind |
| How do competitive inhibitors work? | binds to the active site of the enzyme and obstructs it so the substrate cannot bind |
| How do sulfa drugs inhibit the growth of bacteria? | competes for the active site on the enzyme that converts PABA to folic acid. The folic acid is required for the synthesis of DNA and RNA |
| Why do sulfa drugs not harm the human host? | we do not make folic acid in our bodies |
| What are the three subpathways of aerobic cellular respiration? | glycolysis, tricarboxylic acid cycle (TCA), electron transport chain |
| What is the starting product in glycolysis? | glucose |
| What is the ending product of glycolysis? | 2 pyruvate, 2 NADH, 2 ATP |
| What is the starting product in the transition reaction? | 2 pyruvate |
| What is the ending product in the transition reaction? | 2 acetyl CoA, 2 CO2, 2 NADH |
| What is the beginning product of the TCA cycle? | 2 acetyl CoA |
| What is the ending product of the TCA cycle? | 2 ATP, 6 NADH, 4 CO2 |
| What is the beginning product of ETC (electron transport chain)? | electron carriers |
| What is the ending product of ETC(electron transport chain)? | 34 ATP and some H2O |
| What is the final electron acceptor and what would happen without it? | O2 and ETC would stop without it. |
| Where does electron transport chain take place? | occurs within the cell membrane of bacteria |
| Where does glycolysis happen? | cytoplasm of bacteria |
| Where does TCA cycle happen? | cytoplasm of bacteria |
| If an organism lacks an electron transport chain or a suitable inorganic terminal electron acceptor is not available, what might it use? | fermentation |
| The TCA cycle completes the _______________of glucose | oxidation |
| Coenzymes are: | organic cofactors |
| When a cell processes glucose or other organic molecules through its central metabolic pathways, it does so to generate what three critical items? | ATP, reducing power, precursor metabolites |
| The process that links the electron transport chain to ATP synthesis is called: | the chemiosmotic theory |
| Most coenzymes are derived from: | vitamins |
Created by:
angepu
Popular Biology sets