Intro, Bacterial cell structures, ID, Growth, Culturing

What is microbiology?
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Which of the major categories of life contain pathogens?Bacteria, animals, protists (protozoans, algae), fungi (molds, yeasts)Which of the major categories of life do not contain pathogens?Archaea, plants, fungi (macrofungi)What is the proper way to write scientific names (binomial nomenclature)?-Genus (capitalized) and species -If written: Underlined -If typed: ItalicsKnow which bacterial cell structures are in all bacteria, and which are only in some.-All: Plasma membrane, nucleoid, ribosomes -Some: Glycocalyx, flagella, fimbriae, pilli, bacterial cell walls (almost all), endosporesWhat is a glycocalyx?Sugar coat, composed primarily of polysaccharide carbohydrates, which forms a gelatinous coat that surrounds the cellWhat are the 2 types of glycocalyx?Capsule and slime layerWhat are the characteristics of the capsule?-Highly organized -Tightly adhered to the cell -When bacteria with a capsule are stained using a capsule stain, the capsule appears as a halo surrounding the cellWhat are the characteristics of the slime layer?-Slime consistency -Not well-organized -Loosely adhered to the cellWhat are the functions of a glycocalyx?-Protect the bacteria against host body defenses, desiccation, and chemicals -Allows the bacteria to adhere to surfaces, which aids in the formation of biofilmsWhat is the function of pilli?-Aid in attachment to surfaces -Specific type (F pilus) transfers DNA between bacterial cells during conjugationWhat is the function of fimbriae?Used for attachmentWhat is the function of flagellae?Allow for movement in aqueous environmentsWhat are the differences between pili, fimbriae, and flagellae?-Fimbriae are shorter, thinner, and straighter than flagella and are bristle-like with hundreds per cell -Pilli are longer than fimbriae with only 1-2 per cellName/identify the different arrangements of flagellae.Monotrichous, amphitrichous, lophotrichous, peritrichousWhat is the monotrichous arrangement of flagella?Single flagellum at one pole (end) of the bacteriaWhat is the amphitrichous arrangement of flagella?A flagella (or tuft of flagella) at each poleWhat is the lophotrichous arrangement of flagella?Tuft of multiple flagella located at one poleWhat is the peritrichous arrangement of flagella?Numerous flagella covering the entire cellHow are bacterial flagellae different from mammalian flagellae (e.g. sperm?)Mammalian flagella move back and forth like a snake, whereas bacterial flagella spin like a propellerWhat is an F pilus?Specific type of pilliWhat is the function of F pilus?Transfers DNA between bacterial cells during conjugationWhat is the basic structure of the bacterial peptidoglycan cell wall?-Peptidoglycan consists of sugars alternating to form long polymer strands -Strands are linked at their NAM components by peptide cross-bridges -The strands and cross-bridges form a mesh-like structure that is porous, strong, and flexibleWhat is the primary function of the bacterial peptidoglycan cell wall?Protects the cell from osmotic lysisHow does the bacterial peptidoglycan cell wall protect against lysis?It is strong enough to resist osmotic pressureWhat are the main differences between Gram positive and Gram negative cell walls?-Gram+ has a thick layer of peptidoglycan and will stain purple -Gram- has a thin layer of peptidoglycan and will stain pinkWhat are outer membranes and where are they found?Phospholipid bilayer located on the outside of the gram negative cell wall, separate from the plasma membraneWhy are all Gram negative bacteria inherently pathogenic?Because all Gram negative bacteria contain Lipid AWhat is an endotoxin?A toxin that is a structural part of the bacteriaWhat is the specific endotoxin found in the outer membrane?Lipid AHow many semipermeable membranes do Gram positive bacteria have?1How many semipermeable membranes do Gram negative bacteria have? Why is this clinically relevant?2, makes it much more difficult for substances to cross into the cell compared to Gram+ bacteriaWhat does the cell envelope consist of in Gram negative bacteria?Outer membrane + cell wall + plasma membrane, and porinsKnow the locations of the glycocalyx, cell wall, and plasma membrane in relation to each other in Gram positive bacteria.From inside to outside: Plasma membrane, cell wall, glycocalyxKnow the locations of the glycocalyx, cell wall, and plasma membrane in relation to each other in Gram negative bacteria.From inside to outside: Plasma membrane, cell wall, outer membrane, glycocalyxWhat genus of bacteria has mycolic acids in their outer membrane?Mycobacterium spp.What consistency are mycolic acids?Wax-like substanceHow does the wax-like consistency of mycolic acids benefit the bacteria?It forms a formidable barrier to dehydration and potentially toxic substances, making the outer membrane relatively impermeableWhat differential stain must be used to detect mycolic acids?Acid fast stainWhat are Mycoplasma?A variety of species that are of veterinary importance, including those that cause respiratory disease and hemolytic anemiasHow are Mycoplasma cell walls unique?They have no cell wallHow is the lack of cell walls in Mycoplasma spp. clinically relevant?Antibiotics that target the cell wall are completely ineffectiveWhat is the composition of bacterial plasma membranes?Contain phospholipid bilayer with embedded proteinsWhat is the function of bacterial plasma membranes?Movement of substances through the membraneHow do phospholipids arrange themselves in the plasma membrane?Polar hydrophilic heads face away from the inner membrane and non-poplar hydrophobic tails face towards the inner membraneWhat kind of substances can diffuse directly through the plasma membrane?Small, non-polar substancesWhat kind of substances can't diffuse directly through the plasma membrane?Large and/or polar moleculesWhat is osmosis?Facilitated diffusion of waterDescribe what happens to bacteria in isotonic environments.Water moves through the channel proteins equally in both directionsDescribe what happens to bacteria in hypotonic environments.Water will flow into the cell, which will expand and eventually lyseDescribe what happens to bacteria in hypertonic environments.Water will flow out of the cell, which will lose volume, shrink, and dieWhat is passive diffusion?Molecules diffuse down their concentration gradient directly through the membrane until equilibrium is reachedWhat is facilitated diffusion?Involves a channel protein, but still passive and still diffusing from high to low concentration down the concentration gradientWhat is active transport?Requires energy and involves moving a substance against its concentration gradientWhat is the nucleoid?Region in the prokaryotic cell that contains the chromosomeWhat is the difference between the nucleoid in prokaryotic cells and the nucleus in eukaryotic cells?The nucleoid is not enclosed within a membrane, therefore it is not a nucleusWhat kind of chromosome do bacteria have?Single, circular chromosomeAre bacteria chromosomes haploid or diploid?HaploidHow do bacteria reproduce?ConjugationDo bacteria reproduce via vertical or horizontal gene transfer?HorizontalWhat are plasmids?A small, circular molecule of DNA that typically contains a few genesCan bacteria live without plasmids?YesWhat is the function of plasmids?Allows genes for antibiotic resistance to be transferred from one cell to anotherHow are plasmids transferred between bacteria?-Donor cell extends F pilus to another cell, attaches it and pulls it closer -The 2 cells bridge their cytoplasms -Donor cell transfers plasmid to recipient cellWhat is the function of an endospore?Allow bacteria to survive desiccation, heat, and harmful chemicalsWhat is sporulation?Endospore formationUnder what conditions does sporulation take place?Unfavorable environmental conditionsWhat is germination?Reverting to a growing state (aka vegetative state) once environmental conditions become favorable againWhat two pathogenic genera of bacteria form endospores?Bacillus spp. and Clostridium spp.How are prokaryotic ribosomes different from eukaryotic ribosomes?-Different shape -Smaller than eukaryotic ribosomesHow are the differences between prokaryotic and eukaryotic ribosomes clinically relevant?-Many antibiotics work by targeting bacterial ribosomes -These drugs selectively inhibit the smaller bacterial ribosomes, while sparing the larger eukaryotic ribosomes of the host animalWhat are the ways we can identify bacteria?Morphology, physiologic characteristics, serologic characteristics, geneticsWhich 2 ways are the most common ways to identify bacteria?Morphology and physiological characteristicsHow are basic stains used to visualize cells?-The chromagen in a basic stain has a bound H+, so it is positively charged -When it comes in contact with the bacterial surface (negative charge) it will bind to the bacteria and color itHow are acidic stains used to visualize cells?-The chromagen in an acidic stain has donated a proton, so it has a negative charge -These chromagens bind to the background and color itWhat is the difference between simple and differential staining?-Simple stains use 1 dye and only provide some morphology information -Differential stains use 2 or more dyes and allow differentiation between groups of bacteriaName one example of a simple stain.Safranin, methylene blueName two examples of differential stains.Gram stain, acid-fast stainList the steps of the Gram stain in order.-Apply primary stain (crystal violet) to heat-fixed smear -Apply mordant (Gram's iodine) -Rapid decolorization with alcohol, acetone, or a mix of both -Counterstain with safraninWhat is the purpose of crystal violet stain?Stains Gram+ bacteria purpleWhat is the purpose of Gram's iodine?Causes crystal violet to penetrate and adhere to the Gram+ bacteriaWhat is the purpose of rapid decolorization?-Dehydrates cell wall and serves as a solvent to rinse out the dye-iodine complex -In Gram- bacteria, it will dissolve outer membrane and aid in releasing crystal violet dyeWhat is the purpose of safranin stain?Used as a counterstain to stain the Gram- bacteria that has been decolorizedWhat features are included in cell morphology?Cell size, shape, arrangementKnow the approximate size of a bacterial cell.About 1 micrometer on averageHow does the size of a bacterial cell relate to the typical size of a virus and a eukaryotic cell?Bacteria are significantly smaller than eukaryotic cellsDescribe coccus shape.SphereDescribe bacillus shape.RodsDescribe vibrio shape.Comma-shapedDescribe coccobacillus shape.Intermediate between coccus and bacillus, "short rod"Describe spirillum shape.Thick, flexible, wavy shapeDescribe spirochete shape.Thin, flexible, corkscrew shape; longer than spirillumDescribe diplococcus arrangement.Pair of cocciDescribe staphylococcus arrangement.Cluster of multiple cocciDescribe streptococcus arrangement.Chain of multiple cocciDescribe diplobacillus arrangement.Pair of bacilliDescribe streptobacillus arrangement.Chain of bacilliWhat does pleomorphic mean?Can take a variety of shapesWhat does palisades mean?>1 cell forming T or V shapesWhich bacteria have pleomorphic shapes?Mycoplasma spp. and Corynebacterium spp.Which bacteria form palisades?Corynebacterium spp.What are the different categories of colony morphology?Form, elevation, margin/border, pigment, density, textureWhat is the difference between cell morphology and colony morphology?Colony morphology is the characteristics of a bacterial colony growing on agar, whereas cell morphology is focused on a single cellBriefly describe the process of binary fission in prokaryotes.-Parental cell duplicates its DNA -Cell elongates, separating the DNA copies to each side of the cell -Cross wall forms down the middle of the cell and the plasma membrane invaginates -Cross wall finishes forming down the middle -Two daughter cells separateAre daughter cells different from or identical to the parent cell?IdenticalWhat are two mechanisms that allow for genetic diversity in bacteria?Mutations and conjugationIs mutation or conjugation horizontal gene transmission?ConjugationWhat are the phases of bacterial growth in culture?-Lag phase -Log phase -Stationary phase -Death or decline phaseWhat is the difference between logarithmic and arithmetic growth?-The slope for arithmetic growth is sustained and even, but not very steep -The slope for logarithmic growth is very steep and creates a J-shaped graphDoes logarithmic or arithmetic growth result from binary fission?Logarithmic growthWhat are persister cells?Few cells that survive the death phaseWhat is the significance of persister cells?If conditions improve, they will re-enter the log phase and the resulting population will be more resilient than the originalWhat are the categorizations of life based on oxygen requirements?Obligate aerobes, obligate anaerobes, facultative anaerobes, microaerophilesWhat are obligate aerobes?Generate ATP by aerobic respiration and cannot survive without O2What are obligate anaerobes?Generate ATP through non-aerobic means and exposure to O2 is lethalWhat are facultative anaerobes?Can generate ATP by aerobic respiration, fermentation, or anaerobic respiration, making them highly versatileWhat are microaerophiles?Aerobes that require oxygen levels from 2-10%What are reactive oxygen species (ROS) and why are they important?-Forms of oxygen with at least one unpaired electron -They damage macromolecules and cripple the cellWhat is the function of catalase?Enzyme that converts H2O2 to H2O and O2What is the catalase test?Determines whether bacterial cells have the catalase enzymeWhat are the categorizations of life based on temperature requirements?Psychotrophs, mesophiles, thermophiles, hyperthermophilesIn which temperature requirement category do most pathogens belong?MesophilesWhat are psychotropes?Grow best between 0-20°CWhat are mesophiles?Grow best at moderate temperature, 10-40°CWhat are thermophiles and hyperthermophiles?Grow best at high temperatures, 45-110°CWhat are the categorizations of life based on pH requirements?Neutrophiles, acidophilesWhat are neutrophiles?Grow best in a narrow range around neutral pH, 6.5-7.5What are acidophiles?Grow best in acidic conditions, <5.5What are the categorizations of life based on salinity requirements?Non-halophiles, osmotolerant (aka facultative halophiles)What are non-halophiles?Sensitive even to low salt concentrationsWhat are osmotolerant (facultative halophiles)?Tolerate moderately high salt concentrationsWhat is a biofilm?A biological system that is attached to a surface and usually involves complex relationships between multiple microorganismsWhy are biofilms clinically significant?Removal of a biofilm from living tissue is extremely difficult, thus they have a high risk of creating chronic infections that require ongoing treatment/managementHow do biofilms form?-Usually starts with a pioneer species that can attach to the surface -The pioneer species secretes a glycocalyx, which acts as an extracellular matrix and allows other microorganisms to attach -As the biofilm grows, it becomes highly organized with layers of microbes embedded in glycocalyxHow do biofilms spread?Some individual cells leave the biofilm to multiply and colonize new locationsWhat characteristics of biofilms make them difficult to remove from surfaces and clear from living tissues?-They are tightly attached to the surface and/or each other -Being embedded in the glycocalyx protects them from the immune system, chemical disinfectants/antiseptics, and antibiotics -They share antibiotic resistance plasmids with each other and communicate in order to respond as a single colony to environmental changesWhat does inoculum mean?Bacterial sampleWhat does inoculate mean?Removing an inoculum from a source and introducing it into a growth mediumWhat does culture mean? (as a verb and noun)-Verb: Growing organisms in a lab -Noun: The microorganisms themselvesWhat is culture medium?Material used to culture bacteria in the labWhat is agar?Commonly added to liquid culture media in order to make it solidWhat are the different physical states of media?Liquid, solid, semi-solidWhat is the purpose/function of solid media?Growth of discrete colonies that are pure cultures, allowing for differentiation of multiple speciesWhat is the purpose/function of semi-solid media?Used to determine if a bacterial species is motile (has flagella)What is the difference between complex and defined media?-Complex media contains extracts of yeasts, animal tissues, or plants, providing all the nutrients needed for growth -Defined media has a chemical composition that is designed and formulated for specific needs, thus it usually doesn't have a wide variety of nutrientsWhat are the purposes/functions of selective media?Suppresses the growth of microbes we're not interested in, while supporting the growth of microbes we wantWhat are the purposes/functions of differential media?Allows rapid differentiation between groups of bacteriaWhat technique is used to obtain pure cultures?Streak plate methodWhat does CFU stand for?Colony forming unitWhat is CFU?The progenitor from which a colony on a plate arose fromWhy is it necessary to preserve cultures?If it's not preserved, it will continue to grow logarithmically until the nutrients in the media are depleted and waste products accumulate to toxic levels, then the culture will dieWhat are the methods of preserving cultures?Refrigeration, deep-freezing, ultra-freezing, freeze-drying (aka lyophilization)How long does refrigeration keep a culture alive?Short-term, up to a few weeksHow long does deep-freezing keep a culture alive?YearsHow long does ultra-freezing keep a culture alive?Decades, 30+ yearsHow long does freeze-drying keep a culture alive?Decades, 30+ yearsWhat are the four biosafety levels?BSL-1, BSL-2, BSL-3, and BSL-4 pathogensWhich is the least dangerous biosafety level?BSL-1 pathogensWhich is the most dangerous biosafety level?BSL-4 pathogensWhich level(s) of biosafety are you most likely to work with in clinical practice?BSL-1 and BSL-2 pathogensWhat does sterilization mean?Destruction of all microbial life on an inanimate object, including persister cells and endosporesWhat does disinfection mean?Reducing or destroying microbes on inanimate objects by exposure to an antimicrobial chemicalWhat does antisepsis mean?Reduce or destroying microbes on living tissue by exposure to an antimicrobial chemicalWhat does degerming mean?Mechanical removal of microbes from a limited area, may also include antimicrobial chemicalsWhat does pasteurization mean?Reducing microbe numbers in food products by brief exposure to high heatWhat does sanitization mean?Reducing microbial numbers on an inanimate object to acceptable safe public health standardsWhich cleaning measures are used for use on fomites?Disinfection, sanitization, sterilizationWhich cleaning measures are used for use on living tissues?Antisepsis, degermingIs bacterial death arithmetic or logarithmic?LogarithmicWhat is the D-value?Decimal reduction time, the time it takes to kill 90% of the populationWhat are the factors that determine effectiveness of antimicrobial control methods?-Number of microbes -Environmental condition -Time of exposure -Concentration of disinfectant -Microbial characteristicsWhat are physical methods of growth control?Heat, UV light, gamma radiation, membrane filtrationName examples of physical methods of growth control.Boiling, autoclaving, incinerationWhat are chemical methods of growth control?Phenols, halogens, alcohols, chlorhexidine, peroxides, quaternary ammonium compounds, chemical sterilantsName examples of chemical methods of growth control.Povidine-iodine, sodium hypochlorite (bleach), 70% isopropyl alcohol, formaldehyde, ethylene oxideWhat is one example of a physical method of growth control that achieves sterilization?Autoclaving or gamma radiationWhat is one example of a chemical method of growth control that achieves sterilization?Formaldehyde or ethylene oxideWhich is more effective, moist heat or dry heat?Moist heatWhat is the most effective and practical method of sterilization in the veterinary practice?Autoclaving