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pearson_micro_Ch06
pearson microbiology Bauman Chap 6
| Question | Answer |
|---|---|
| Microbial Growth is ________ | an increase in a population of microbes rather than an increase in size of an individual |
| discrete colony is ________________ | an aggregation of cells arising from a single parent cell |
| Organisms that use an inorganic source of carbon (Carbon dioxide) are called ______________ | Autotrophs |
| Organisms that catabolize reduced organic molecules (proteins, carbohydrates, amino acids, and fatty acids) are called ______________ | Heterotrophs |
| Organisms that acquire energy from Redox reactions involving Inorganic and Organic chemicals are called ______________ | Chemotrophs |
| Organisms that use light as their energy source are called ______________ | Phototrophs |
| What is the name for organisms that must have oxygen to survive? | Obligate Aerobes |
| what is the name for organisms that are poisoned by oxygen and cannot tolerate it? | Obligate Anaerobes |
| Singlet Oxygen is _________ | molecular oxygen with electrons boosted to higher energy state (usually during Aerobic Metabolism) |
| Phototrophic organisms have these to remove the excess energy of Singlet Oxygen | Carotenoids |
| Which organisms can maintain life via Fermentation or Anaerobic Respiration or by Aerobic respiration | Facultative Anaerobes |
| What does not use Aerobic Metabolism, but do have some enzymes that detoxify oxygen's poisonous forms, so can grow in its presence | Aerotolerant Anaerobes |
| Aerobes that require Oxygen levels from 2-10% and have a limited ability to detoxify Hydrogen Peroxide and Superoxide Radicals are ______ | Microaerophiles |
| Insufficient Nitrogen for proteins and nucleotides | What normally causes anabolism to cease? |
| Phosphorus | What is required for DNA, Phospholipid membranes, RNA, ATP, and some proteins? |
| Trace Elements | Usually found in sufficient quantities in tap water |
| Growth Factors | organic chemicals that cannot be synthesized by certain organisms (Vitamins, Essential Amino Acids, Purines, Pyrimidines, Cholesterol, NADH, and Heme) |
| effect of low temperature on lipid-containing membranes of cells and organelles | makes them rigid and fragile |
| categories of microbes based on temperature range | psychrophiles, mesophiles, thermophiles, and hyperthermophiles |
| psychrophiles | those that grow best at about 15 degrees celcius; can grow below 0 degrees celcius, but not much above 20 degrees celcius |
| mesophiles | those growing best between 20 degrees and 40 degrees celcius; the human pathogens are in this group |
| thermophiles | those that grow above 45 degrees celcius; occur in hot springs and compost piles |
| hyperthermophiles | Archaea growing about 80 degrees celcius and some above 100 degrees celcius |
| Neutrophiles | microbes that grow best in a narrow range around neutral pH (6.5-7.5); includes most bacteria an protozoa |
| Acidophiles | those that grow best in acidic habitats; include other bacteria and fungi |
| acidic waste products | what can help preserve food by preventing further microbial growth? |
| alkalinophiles | microbes that live in alkaline soils and water up to pH 11.5 |
| why microbes require water | to dissolve enzymes and nutrients require in metabolism; also because it is an important reactant in many metabolic reactions |
| endospores and cysts | what cease most metabolic activity in a dry environment for years? |
| osmotic pressure and hydrostatic pressure | what are the 2 physical effects of water? |
| osmotic pressure | pressure exerted on a selectively permeable membrane by a solution containing solutes that cannot freely cross the membrane; related to concentration of dissolved molecules and ions in a solution |
| hypotonic solutions | those with lower solute concentrations and higher water concentrations; cells placed in these solutions gain water; and if they lack a cell wall, may burst |
| hypertonic solutions | those with higher solute concentrations and lower water concentrations; cells placed in these solutions undergo CRENATION |
| Crenation | shriveling of cytoplasm; this effect helps preserve some foods |
| obligate halophiles | those that grow in up to 30% salt |
| facultative halophiles | those that do not require, but can tolerate high salt concentrations |
| Barophiles | organisms that live under extreme pressure |
| Hydrostatic pressure | Barophiles' membranes and enzymes depend on this pressure to maintain their 3-dimensional, functional shape |
| Antagonistic relationships | those in which one organism harms or kills another |
| Synergistic relationships | those in which organisms cooperate for the benefit of both |
| Symbiotic relationships | those in which organisms are in such close physical or nutritional contact they become interdependent |
| Biofilms | complex relationships among numerous individual microorganisms |
| Quorum Sensing | biofilms form on surfaces often as a result of what? |
| Quorum Sensing | microbes respond to density of nearby microbes |
| Inoculum | sample of a microbe that is introduced into a Medium |
| Medium | collection of nutrients that may be liquid (broth) or solid (usually agar) |
| Environmental, Clinical, Stored | the three types of specimens from which the inoculum comes |
| Culture | act of cultivating microorganisms, or the microorganisms that are cultivated |
| Pure Cultures | those compouds of cells arising from a single progenitor |
| progenitor | may be a single cell or a group of related cells; termed CFU (Colony-Forming Unit) |
| Aseptic technique | used to prevent contamination of sterile substances or objects |
| Streak Plates and Pour Plates | Two common isolation techniques |
| Streak Plates | isolation technique using a sterile loop or needle to spread inoculum across surface of solid medium to isolate CFUs |
| Pour Plates | isolation technique using a series of serial dilutions to separate CFUs |
| Six types of General Culture Media | Defined Media, Complex Media, Selective Media, Differential Media, Selective and Differential Media, Anaerobic Media, Transport Media |
| Defined Media | those in which the exact chemical composition is known |
| Complex Media | those in which the exact composition is unknown, but contains a variety of nutrients and growth factors |
| Selective Media | those which favor growth of certain microbes or inhibit growth of others; contain selective agents--Sabouraud Dextrose Agar |
| selective agents | eosin, methylene blue, bile salts, high NaCl |
| Differential Media | those that show changes in the medium or in the appearance of colonies grown on them --Blood Agar |
| Selective and Differential Media | those that both favor growht of certain species and enable differentiation among them by their effect on media or appearance of their colonies |
| Selective and Differential Media | Mannitol Salt Agar, MacConkey Agar, Eosin-Methylene Blue Agar |
| Anaerobic Media | those that encourage growth of Anaerobes --Sodium Thioglycollate Broth |
| Transport Media | those used to transport clinical specimens (various body fluids) to prevent them from being contaminated, or infecting other people |
| Animal and Cell Culture, Low-Oxygen Culture, and Enrichment Culture | Special Media Techniques |
| Animal and Cell Culture | used to grow very fastidious organisms or Obligate Intracellular Parasites (Viruses, Rickettsias, Chlamydias) |
| Low-Oxygen Culture | use CO2 Incubators or Candle Jars to favor growth of Aerotolerant Anaerobes, Microaerophiles, and Capnophiles(microbes growing best at high CO2 and low O2 levels) |
| Enrichment Culture | used to enhance growth of microbes present in very small numbers; sometimes Cold-Enrichment |
| Cold-Enrichment | sometimes used to enhance the growth of microbes present in very small numbers by using a refrigerator to enhance the growth of cold-tolerant species (Vibrio sp.) |
| refrigeration, deep-freezing, and Lyophilization | ways to preserve cultures |
| refrigeration | used for short-term storage |
| deep-freezing | used for long-term storage; maintaining temperatures between -50 degrees celcius and -95 degrees celcius) |
| Lyophilization | used for very long-term storage; freeze-drying- removing water from frozen culture using intense vacuum converting ice directly into a gas |
| Binary Fission | most UNICELLULAR microorganisms reproduce by what method? |
| Binary Fission | reproduction process in which a cell replicated its DNA, grows to twice its normal size, then divides in half, forming two new cells; with each division, the number of cels doubles, increasing by multiples of two |
| Logarithmic (Exponential) Growth | that in which there is a doubling of the number of cells in the population with each generation |
| Generation time | time required for cell to grow and divide |
| Growth Curve | graph of the number of organisms in growing population over time |
| Lag, Log, Stationary, Death | List the four distinct phases in the population's growth curve of a microorganism growing in a liquid medium |
| Viable Plate Counts, Membrane Filtration, Microscopic counts, Electronic counters, most probable number | list the 5 DIRECT METHODS of measuring microbial growth (In the order they were listed in our notes) |
| Membrane Filtration | direct method for measuring microbial growth where the number of microbes in a liquid sample is determined by trapping organisms on a fine membrane filter; transferring it to solid culture medium, allowing colonies to grow and counting them |
| Which of the following could be an optimal pH for the growth of an acidophile? pH 7.0 pH 11.0 pH 8.5 pH 3.0 | 3.0 |
| A cell that uses an organic carbon source and obtains energy from light would be called a __________. | chemoheterotroph |
| Which of the following is NOT a toxic form of oxygen? peroxide anions, hydroxide ion, superoxide radicals, singlet oxygen | hydroxide ion |
| Which of the following groups of microbes does not undergo aerobic metabolism, but can detoxify oxygen enough to live in its presence? facultative anaerobes, aerotolerant anaerobes, microaerophiles, obligate anaerobes | aerotolerant anaerobes |
| Nitrogen is rarely a growth-limiting nutrient. T/F | False Nitrogen is frequently a growth-limiting nutrient because cells need it to produce proteins and nucleic acids, without which they cannot grow and reproduce. |
| Nitrogen is essential for the production of amino acids and nucleotide bases. T/F | True |
| All cells can recycle nitrogen from their nitrogen-containing molecules. T/F | True |
| Only a few types of bacteria can engage in nitrogen fixation. T/F | True |
| Organic molecules that prokaryotic organisms need, but cannot synthesize by themselves, are called __________. | growth factors |
| A microbe isolated from deep in the ocean could best be characterized as a __________. | barophile and psychrophile |
| In the streak plate method of isolation colonies will be found growing at and below the surface of the medium. T/f | False |
| Extension of the microbial growth phase is an advantage conferred on microbial cells by a biofilm? T/F | False |
| Why is agar a useful substance in the microbiology lab? | Agar does not solidify until it cools to about 40°C. |
| Which of the following is both a selective and a differential medium? blood agar, MacConkey agar, nutrient broth, Sabouraud dextrose agar. | MacConkey agar |
| A psychrophile might grow best in which of the following environments: the human body, a candle jar, a refrigerator, a thermal pool | a refrigerator |
| A candle jar would be most useful in isolating which of the following: fastidious microbes, biofilms, capnophiles, psychrophiles | capnophiles |
| A bacterial species has been determined to have a generation time of 30 minutes. If a microbiologist starts with an inoculum of 1000 cells/ml, and wants to grow it to a culture of 1,000,000 cells/ml, approximately how long should the culture be incubated? | 5 hours |
| Bacterial cultures go through lag phase because __________. | they are synthesizing new enzymes in order to use nutrients in their medium |
| Concerning the bacterial growth , when death phase is reached, all cells in the culture have died T/F | False |
| Turbidity is a direct method of measuring microbial growth T/F | False |
| If a cell counter slide is determined to have a mean number of 20 bacterial cells per square, the total number of bacteria per ml of culture would be __________. | 25,000,000 In a typical Petroff-Hauser counting chamber, the factor by which the number of cells is multiplied is 1,250,000. (20 × 1,250,000 = 25,000,000) |
| The MPN (most probable number) method of measuring microbial growth is one of the easiest and quickest methods. T/F | False |
| Flow cytometry involves the counting of cells that have fluorescent dyes associated with them. T/F | true These fluorescent dyes either are used to stain the cells or are attached to the cells by means of antibodies. |
| Direct methods of measuring microbial growth are more accurate than indirect methods. T/F | False Both of these types of methods are merely ways of estimating the actual number of microbial cells present. |
| Bacterial growth curves are plotted on graphs that have a logarithmic scale on both the x- and y-axes. T/F | False Only the y-axis has a logarithmic scale, which is why these graphs are often called semilogarithmic. |
| The quantity n2 represents the number of cells that arise from a cell that reproduces by binary fission. T/F | false 2n is the formula for cells dividing by binary fission, where n = the number of generations. |
| Cells that divide by binary fission in different planes produce a chain formation of cells. T/F | false When divisions occur in different planes, a cluster of cells is formed. |
| Blood agar is an example of a complex medium. T/F | True Since it contains actual blood, blood agar supplies a variety of growth factors, making it a complex medium. |
| Facultative halophiles do not require the presence of high salt concentrations in order to grow. T/F | false Only obligate halophiles require high salt concentrations in order to grow. |
| Bacteria that are pathogenic for humans are usually classified as mesophiles. T/F | true |
| When organisms are exposed to temperatures higher than their maximum growth temperature, their proteins are permanently denatured. T/F | True When an organism's proteins are denatured, it will die. |
| Most bacterial cells divide using a process called binary fusion. T/F | False Fusion means to join together. Bacterial cells divide using binary fission, not fusion. |
| Refrigeration kills all bacterial cells except psychrophiles. T/F | False Refrigeration will not kill most bacterial cells. Instead, it simply slows their metabolism and prevents them from reproducing. |
| Nitrogen fixation __________. | involves reduction of nitrogen gas to ammonia |
| The majority of bacteria and archaea have not or cannot be grown in the laboratory. T/F | true Only a relatively small number of species of bacteria and archaea have been grown in the laboratory. |
| The term lithotroph is used to describe organisms that __________. | obtain their electrons or hydrogen ions from an inorganic source |
| A reducing medium is most often used for growing fastidious bacteria that have very specific nutritional requirements. T/F | False A reducing medium is used to grow obligate anaerobes, while an enrichment medium is most often used for growing fastidious bacteria that have very specific nutritional requirements. |
| Quorum sensing is __________. | a process used by bacteria to detect population density and activate genes for new characteristics |
| Which of these media is NOT an example of a differential medium: MacConkey agar, carbohydrate utilization broth, blood agar, trypticase soy agar | trypticase soy agar This medium distinguishes bacteria that can utilize a specific carbohydrate from those that cannot, usually by a pH change |
| When performing serial dilutions and viable plate counts, the concentration of microorganisms is usually expressed as number of bacteria per milliliter. T/F | False The concentration is expressed in colony-forming units, or CFU, per milliliter. |
| Most pathogenic bacteria would be classified as __________. | chemoheterotrophs |
| A chemostat could be used to keep a bacterial culture in the log phase indefinitely. T/F | true Chemostats remove wastes and add nutrients so that bacteria may remain in the log phase indefinitely |
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