MIBO 3500 Final Exam Questions With Correct Answers

Microbial size definition - Answer organisms and acellular agents too small to be seen by the unaided eye contradictions to this definition - Answer -supersize microbial cells -microbial communities -viruses You are caring for a patient actively infected with Mycobacterium tuberculosis. Size of contaminated respiratory droplets are nm in size. Standard surgical masks are designed to block particles larger than 5 μm. Will wearing a standard surgical mask be an effective form of protection? - Answer No, the mask protects against microbes that are 1-5 nanometers, and the tuberculosis particles are larger than 5 nanometers Robert Hooke - Answer -built first compound microscope to observe mole and cork -published Micrographia -coined the term "cell" Antoine van Leeuwenhoek - Answer -built single lens magnifiers -first to observe single-celled microbes, called them "small animals" Francesco Redi - Answer performed an experiment disproving spontaneous generation in which he had meat in a container with no cover, one with a paper cover, and one with a gauze cover Lazzaro Spallanzani - Answer disproved spontaneous generation by boiling broth and either covering it or not covering it. Observed microbial presence in broth that had no cover only Louis Pasteur - Answer disproved spontaneous generation using broth and bottle-neck experiment spontaneous generation - Answer living organisms can arise from non-living matter Germ theory - Answer the theory that many diseases are caused by microbes (chain of infection, pure culture, colonies) Chain of infection - Answer transmission of infectious microbes Pure culture - Answer culture from a single parental cell Colonies - Answer distinct populations each grown from a single cell Robert Koch - Answer Developed first guidelines (postulates) to establish a link between a specific microbe and disease Koch's postulates (4) - Answer 1) Microorganism must be present in every case of the disease and absent from healthy organisms 2) Microbe must be isolated/grown in pure culture 3) Same disease must result when microbe is inoculated in healthy host 4) Same microorganism must be able to be isolated from the host in which inoculation caused disease Florence Nightingale - Answer the first to use medical statistics to demonstrate the significance of mortality due to disease Alexander Fleming - Answer discovered that Penicillium mold generated a substance that can kill bacteria Howard Florey and Ernst Chain - Answer purified penicillin, first commercial antibiotic to save lives Sergei Winogradsky - Answer among the first to study microbes in natural habitats, discovered lithotrophis, and developed enrichment cultures. ALso build Winogradsky column Resolution - Answer the ability to distinguish small objects close together Magnification - Answer enlarged image of an object Contrast - Answer the difference in color intensity between an object and its background 4 types of light microscopes - Answer bright-field dark-field phase-contrast fluorescence Compound microscope - Answer a microscope that forms an image from more than two lenses Images produced by bright field microscopes are real or virtual? - Answer virtual Bright-field microscopy - Answer -used to see small bacteria but cannot be used to see smaller microbes like viruses. Shows cells in colorless fashion. Staining of cells usually kills them and ligt refraction is also problematic Refraction - Answer bending of light as it passes through an object that slows its speed Dark-field microscopy - Answer -dark field optics enable microbes to be visualized as halos of light against darkness -allows detection of narrow cells (0.1 nano) that are unresolved by bright-field microscopy Phase-contrast microscopy - Answer refractive differences in cell components are transformed into differences in light intensity Fluorescence microscopy - Answer For specimens with added dye, or naturally photosynthetic microbes, this way shows bright colored image of object, protein, or structure. Widely used in medical microbiology and ecology Fluorophores - Answer chemical compounds that absorb/emit light of specific wavelengths, can be a dye or a protein Why do researchers stain microbes? - Answer -increases visibility -preserves sample -highlights morphological features Heat fixation - Answer uses flame to preserve internal and external morphology but inactivates enzymes Chemical fixation - Answer uses ethanol, preseves morphology of microbe but may also inactivate enzymes basic dyes - Answer have a POSITIVE charge and bind to negatively charged molecules, such as nucleic acids or bacterial surfaces 3 basic dyes - Answer -methylene blue -crystal violet -safranin Acidic dyes - Answer have a negative charge that binds to positively charged molecules, such as tissue 2 acidic dyes - Answer eosin and nigrosin simple stains - Answer add color to the cells but not background Differential staining definition and 3 types covered in class - Answer stains one kind of cell but not another -gram -acid fast -endospore Gram staining - Answer differential staining based on cell wall properties Acid-fast staining - Answer differential staining based on lipid content in cell walls Endospore staining - Answer differential staining based on vegetative and dormant spores Peptidoglycan - Answer rigid structure that lies just outside of plasma membrane Gram + bacteria have (thick/thin or no) peptidoglycan layers - Answer thick Gram stain procedure (long) - Answer 1) Add crystal violet, turning all bacteria purple. 2) Add iodine, which traps crystal violet in thick pep layers of gram + bacteria. All bacteria is still purple. 3) Wash sample with alcohol, removing purple color from gram - bacteria; gram = remains purple. 4) Add safranin, which does not affect gram + bacteria, but turns gram _ bacteria red Electron microscopy - Answer electrons are used instead of light beam. Beam wavelength is extremely short, allowing great resolution. Bacilli rods - Answer Paired cocci - Answer Spirochete - Answer cocci in chains - Answer Pilus - Answer each microbe contains only 1-2, they are long, thick protrusions used in DNA transfer between microbes and motility Fimbriae - Answer up to 1000/cell evenly distributed throughout layer. Used for attachment to surfaces Capsule - Answer (glycocalyx) outer layer of polysaccharides used in surface adherence and in resistance to phagocytosis Flagellum - Answer external helical filament whose rotary motor propels the cell, used in swimming and swarming motility 2 ways bacteria move without flagella - Answer 1) by fluid or currents e.g. blood, ocean or air currents 2) Actin polymerization produces actin tails cell membrane - Answer defines the existence of a cell, can contain saturated or unsaturated fatty acids Hopanoids - Answer reinforcing agents in bacterial plasma membrane function of membrane proteins - Answer -structural support -detection of environmental signals -secretion of virulence factors -ion transport diffusion - Answer small uncharged molecules such as CO2 or O2 can easily permeate membrane by diffusion Osmosis - Answer water diffusion across plasma membrane from area of high water concentration to low water concentration Polar/charged molecules - Answer require transport through specific portein transporters cell wall - Answer (sacculus) confers shape and rigidity to the cell and protects cell membrane, some cells have membranes but no walls two sugar precursors in peptidoglycan - Answer N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) gram-positive bacteria's peptidoglycan layers are threaded by what? - Answer teichoic acids Lipoproteins are found in gram (+/-) bacteria - Answer negative lipoproteins function - Answer connects outer membrane to peptidoglycan layer LPS as endotoxins - Answer Lipopolysaccharides overstimulate immune cells when its cell dies, causing a cytokine storm Porins - Answer outer membrane holes that allow passage of nutrients; also site of antibiotic entry S-layer - Answer founf in both gram + and - bacteria, is a crystalline layer of proteins and glycoproteins used to contribute to cell shape and help protect the cell from osmotic stress Nucleoid - Answer region in prokaryotes where DNA is organized into loops or domains Plasmids - Answer circular DNA strands that can replicate independently, often carry unique genes such as antibiotic resistance Genus mycobacterium - Answer membranes contain mycolic acids instead of teichoic acids linked to arabinogalactan that links peptidoglycan Genus mycoplasma - Answer Lack cell walls (pleomorphic) cannot synthesize peptidoglycan uses sterols to stabilize plasma membrane grows as fried egg appearance on agar surface contain three-layered plasma membrane essential nutrients - Answer nutrients a microbe cannot make for itself, but must gather from its environment Macronutrients - Answer nutrients needed in large quantity: C, N, P, H, O, S, Mg, Fe, K, and Ca micronutrients - Answer nutrients needed in small quantities: Co, Cu, Mn, Md, Ni, Zn Enriched media - Answer complex media to which specific blood components are added Selective media - Answer favor the growth of one organism over another Differential media - Answer exploit differences between two species that grow equally well Rickettsie prowawzekii - Answer agent of typhus fever endemic in flying squirrels spread through lice and feces can ONLY grow in eukaryotic cytoplasm Autotrophs - Answer reduce carbon dioxide to get their carbon to make complex cell constituents Heterotrophs - Answer must rely on other organisms to get their carbon. Degrade organic compounds into smaller compounds for energy and then reassemble to make cell constituents, releasing CO2 Phototrophy - Answer receive energy from light Chemotrophs - Answer get their energy from redox reactions classes of chemotrophy - Answer lithotrophy and organotrophy lithotrophy - Answer gets electron source from INorganic molecules Organotrophs - Answer get their electron energy from ORGANIC molecules Pre-fixes - Answer Auto- CO2 is reduced for carbon Hetero- pre-formed carbon source Photo- light captures energy Chemo- redox for energy Litho- inorganic electron donors Organo- organic electron donors Chemical energy source - Answer phosphate groups of ATP molecules are broken down to release enrgy in cells membrane potential energy source - Answer inside of cell is more negatively charged than outside of cell, creating proton gradient plus charge difference forms proton motive force microbes in nitrogen cycle - Answer nitrogen is a macronutrient. Atmospheric N2 must be converted into a usable form (amonnia NH4+) "fixed" Rhizobium - Answer grows symbiotically within root nodules of legumes by infecting the root as a beneficial infection. Relationship provides plant higher nitrogen availability, improving plant health and lowering cost to farmer ATP synthase mechanism of action - Answer 1. Proton flow through rotor subunit by proton motive force 2) Proton flow causes F1 to rotate 3) ATP is synthesized Binary fission - Answer how most bacteria divide, where one parent cell splits into two equal daughter cels exponential growth formula - Answer Nt = N0 x 2^n Nt = total number of cells N0 = original number of cells n = number of rounds of binary fission Bacterial growth curve - Answer Lag phase - Answer Population is metabolically active and number of cells does not increase. Length varies with species and conditions Exponential (log) phase - Answer population doubles each generation and primary metabolites are synthesized. Balanced growth at a constant rate When in bacterial growth curves are the bacteria most susceptible to antibiotics? - Answer exponential phase Primary metabolites - Answer amino acids nucleic acids simple lipids secondary metabolites - Answer antibiotics Stationary phase - Answer growth curve horizontal as population growth ceases. New cells are made at the same rate as old cells die and secondary metabolites are made at beginning Death phase - Answer exponential 99% of population dies Prolonged decline - Answer 1% of population mutates according to environment Continuous culture - Answer a culture in which all cells in a population achieve a steady state, allowing detailed study of bacterial physiology Chemostat - Answer ensures logarithmic growth by constantly adding and removing equal amounts of culture media Biofilms - Answer most bacteria attach to surfaces rather than exist in free-floating states. Attached bacteria form complex, slime enclosed communities called biofilms. Clinically important contributor to microbial disease Biofilm formation (long) - Answer 1) Planktonic cells attach to nearby surfaces and coat surfaces with organic debris that more cells can attach to 2) Exopolysaccharide (EPS) production occurs, producing DNA, sugars, and proteins 3) 3-D towers form and cells may break free if nutrients are depleted. Alzheimer's disease - Answer irreversible and progressive loss of memory, thiking, and ability to perform basic daily activities. Porphyromonas gingivalis - Answer has DNA that can be detected more often in brains of those with Alzheimer's disease normal growth conditions for microbes - Answer -sea level -temp ~20-40C -neutral pH -0.9% salt -ample nutrients Extremophiles - Answer organisms that live outside of normal conditions, (high/low heat, pressure, etc.) Why is temperature regulation important for microbes? - Answer -enzymes have optimal temperature for function -high temps destroy proteins -low temperatures solidify membranes Psychrphiles - Answer 0-20C have enzymes adapted to function in cold temps Membrane remains semi-fluid when cold Microbes accumulate solutes to decrease freezing point How do psychrophiles keep their membrane semi-fluid in cold temperatures? - Answer incorporating high levels of unsaturated fatty acids into their membranes Mesophiles - Answer 15-45C Thermophiles - Answer 40-80C enzymes adapted to function in hot temp Increased hydrogen bonding Less flexible polypeptides Numerous DNA binding proteins stabilize DNA Thermus aquaticus - Answer microbe that can survive in hot temperatures by utilizing TAQ DNA polymerase Taq DNA polymerase - Answer specialized DNA pol that functions in very high temperatures, one of the most widely used enzymes in biotechnology Barophiles - Answer grow at pressures up to 1000 atm or 14600 psi, utilizes hydrostatic pressure to reduce membrane fluidity but other mechanisms for survival in high pressures are a mystery hypertonic medium - Answer medium with high solute concentration Hypotonic medium - Answer medium with low solute concentration Cells in hypertonic media - Answer water will leave the cell in an attempt to equalize solute concentration, bacteria shrinks and dies Cells in a hypotonic medium - Answer Water will enter cell and bacteria will swell, burst, and die. Aquaporins - Answer membrane-channel proteins that allow water to traverse the membrane much faster than by diffusion to protect cell from osmotic stress How do cells adapt to hypotonic environments? - Answer The cell expresses pressure-sensitive channels in plasma membrnae to allow solutes to leave the cell Halophiles - Answer prefer a low internal concentration of sodium How do halophiles maintain an appropriate sodium concentration? - Answer They use ion pumps to excrete sodum and replace it with other cations (potassium) Staphylococcus aureus - Answer microbe found in respiratory tract/skin and 20% of human population are carriers a HALOtolerant microbe that can be cultured in media up to 10% NaCl reactive oxygen species and microbes - Answer oxygen is toxic to all microbes that do not have enzymes capable of efficiently destroying reactive oxygen species Aerobe - Answer grows in presence of oxygen (20%) Obligate aerobe - Answer reauires oxygen Microaerophile - Answer requires oxygen at low concentrations (2-10%) Anaerobe - Answer grows in the absence of O2 Facultative anaerobe - Answer does not require oxygen but grows better with it Aerotolerant anaerobe - Answer grows equally well with or without oxygen optimal pH for microbial growth - Answer 5-8.5