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pearson microbiology Bauman Chap 6

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
Created by: hkrawietz