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MCB 3020
Exam 3
| Term | Definition |
|---|---|
| growth | an orderly increase of all the major chemical constituents of an organism; increase in total mass does not necessarily mean growth because could be increase of reserve material; normally results in cell multiplication |
| multicellular organism growth | results in increase in size of the individual |
| unicellular organism growth | results in increase in the number of individuals |
| binary (transverse) fission | two cells arise from one cell; usually involves an equal partitioning of material (DNA, proteins, etc.) by forming a septum in the middle of the cell where division occurs |
| filamentous temperature sensitive (Fts) proteins | essential for cell division |
| FtsZ | forms the ring in the center of the cell; attracts other divisome proteins |
| Zip A and FtsA | helps anchor FtsZ rings to cytoplasmic membrane |
| FtsI | needed for peptidoglycan synthesis (penicillin binding protein); activity blocked by penicillin |
| FtsK and several other proteins | help the two copies of chromosomes pull apart |
| divisome | responsible for regulating synthesis of new cell membrane and wall material |
| MinE protein | directs formation of the FtsZ ring and divisome complex at the cell division plane (center of cell); prevents midD from forming |
| MinC and MinD | most abundant at the cell poles and prevent cell division at the poles; midC binds to midD and prevents FtsZ |
| MreB | cytoskeleton protein; actin analog that winds as a coil through the long axis of rod shaped cell, making contact with cell membrane at sites of synthesis |
| autolysins | cut preexisting peptidoglycan |
| bactoprenol | C55 lipid binds peptidoglycan precursors and transports through membrane to be inserted into growing point in cell wall |
| crosslinks | without peptidoglycan crosslinks and new cell wall synthesis, continued activity of autolysins weakens cell wall causing osmotic lysis |
| budding | a type of division which results in unequal distribution material of cellular material newly synthesized in bud and original cell |
| lag phase of bacterial growth | does not always occur in the growth of a bacterial population, and when it does, the duration can vary considerably; k=0; little to no growth; happens because cells need to synthesize all the necessary materials needed in the new environment |
| exponential or log phase of bacterial growth | can not continue indefinitely; limited k=max+; double every generation time |
| stationary phase of bacterial growth | k=0; no increase in cell number or cell mass; occurs because either an essential nutrient is used up or a waste product builds up to an inhibitory level |
| death phase of bacterial growth | k=-; exponential death (slower than exponential growth) |
| turbidity | optical density |
| growth rate | the change in cell number or cell mass per unit time |
| generation time | time required for a doubling (cell divides to produce two cells) to occur; g=t/n (time/number of generations) |
| when can a lag phase occur? | if you inoculate cells from a stationary, death, or exponential phase into a fresh medium of different chemical composition; can not occur if cells growing exponentially are moved into a fresh media of same chemical composition |
| biphasic growth | growth first on most rapidly metabolize C source (glucose) then lag before growth on lactose (new enzymes needed) |
| nepholometer | measures scattered light |
| spectrophotometer | measures light passing through a solution/media |
| direct microscopic count | a small portion (.01-.02 mL) of a bacterial suspension is smeared on a glass slide in a prescribed are (usually 1 cm. sq.); the film is stained and the # of microo. per microscopic field is recorded; desirable to have 1-2 MO per field & to count 50 fields |
| microscopic factor (MF) | (area of film (Af)) / (area of the microscopic field (Amf)) |
| number of microo. per mL in a suspension | (Average # of microo. per field) x (microscopic factor) x (dilution factor) |
| physical environmental factors on growth | temperature, osmotic pressure, and UV radiation |
| chemical environmental factors on growth | water activity, pH, and oxidation-reduction potential |
| sterilization | treatment which frees objects of all living organisms including endospore (autoclaving 15 minutes at 121C and 2 ATM) |
| death | irreversible loss of ability to reproduce |
| enzyme activity | as a general rule, the rate of an enzyme reaction increases 2-3x for every 10C increase in temperature |
| cardinal temperatures | minimum temperature (below which no growth occurs); optimum temperature (growth is most rapid); maximum temperature (above which growth is not possible); optimum is closer to maximum than minimum |
| viable | living (capable of reproduction) |
| psychrophile | optimum temperature of 15C; red pigmented spores |
| mesophile | optimum temperature 37C (human body temperature) |
| thermophile | optimum temperature exceeds 45C |
| hyperthermophiles | optimum temperature exceeds 80C; Archaea; |
| pH | if pH changes one pH unit (ex: 2 to 3) then [H+] changes 10x; most bacteria fall within the pH range of 4-9; |
| water activity (a sub w)= | P (solution) / P (water); most bacteria grow about .95 |
| halophile | require salt for growth |
| osmophiles | require high sugar for growth |
| compatible solutes | solute used inside the cell for adjustment of cytoplasmic water activity; must be noninhibitory |
| cells are normally | hypotonic to the environment BUT halophiles are hypertonic to the environment |
| aerobes | species cable of growth at full oxygen tension (air is 21% O2) and many can tolerate elevated concentrations of oxygen (hyperbaric oxygen) |
| obligate aerobes | aerobes that require O2 for growth; aerobic respiration |
| microaerophiles | aerobes that can use O2 only when it is present and levels reduced from that in air, usually because of their limited capacity to respire or because they have an oxygen-sensitive molecule (required at levels below atmospheric levels); aerobic respiration |
| facultative aerobes | under appropriate nutrient and culture conditions, can grow under either aerobic or anaerobic conditions (O2 not required but generally grow better with it); aerobic or anaerobic respiration or fermentation |
| anaerobes | organisms that cannot respire oxygen (O2) |
| aerotolerant anaerobes (facultative anaerobes) | can tolerate oxygen and grow in its present even though they cannot use it (not required but generally grow no better with it); fermentation |
| obligate (strict) anaerobes | inhibited or even killed by oxygen; fermentation or anaerobic respiration |
| byproducts of electron transport to oxygen | 4 electrons transfer to O2; all intermediates formed are reactive and toxic to cells |
| enzymes to remove toxic byproducts of oxygen metabolism | catalase, peroxidase, superoxide dismutase, superoxide dismutase/catalase in combination, and superoxide reductase; |
| obligate and facultative aerobes typically have both: | catalase and superoxide dismutase (SOD) |
| aerotolerant anaerobes typically lack | catalase BUT have superoxide dismutase (SOD) |
| obligate anaerobes lack both | catalase and superoxide dismutase (SOD) |
| aerobes need extensive aeration: | vigorous shaking of flasks or tubes; bubbling sterilized air through medium |
| anaerobes need | reducing agents like thioglycolate (contains small amount of agar) added; anoxic jar (envelopes generates H2 (reacts with O2 to remove it with Pd) + CO2); anoxic glove box (airlock on right can be evacuated and filled with O2 free gas) |
| normal flora | microorganisms noramlly found in or on the body that typically do not cause disease but are in fact benefitical; established after birth |
| competition | it is the normal flora that protects us against harmful microbes |
| 10x more bacteria than cells on the body | 10^13 human cells; 10^14 bacteria |
| mutualism | both host and microbe benefit; +/+ |
| commennsalism | microbe causes no damage to host; +/0 |
| parasitism | microbe causes damage to host; +/- |
| pathogenic relationship | microbe causes damage to host; +/- |
| synergistically | capable of working together; two microorganisms are synergistic if they are able to produce a host response greater than the sum of the effects they produce when acting alone |
| communicable | able to be transmitted between hosts |
| disease reservoir | a natural source of disease agent; may include sick patients, asymptomatic carriers, animals, recovered patients, environmental sources, etc. |
| parasites | organisms that live on or in a host organism, causing damage to the host |
| pathogens | microbial parasites; some may be carried by healthy individuals but may not cause disease |
| pathogenicity | the ability of the parasite to cause damage on the host and on the resistance or susceptibility of the host to the parasite |
| virulence | the quantitative measure of degree of pathogenicity |
| comprised host | has lower resistance to infection and ultimately disease |
| infection | refers to any situation in which a microorganism is established and growing in or on a host, regardless of whether or not the host is harmed |
| disease | damage or injury to the host that impairs host function |
| infection is not | synonymous with disease |
| infestation | presence of microorganism; not necessarily growing and reproducing |
| normal flora of skin | 10^12 bacteria; apocrine (sweat) glands and sebaceous (oil) glands of hair follicles |
| normal flora of internal tissues | brain, blood, cerebrospinal fluid, and muscles should not have bacteria |
| normal flora of stomach | pH around 2; acidity drops viable count to <10/mL; mycobacteria and salmonella are resistant; helicobacter phlori causes ulcers |
| normal flora of colon | adult eliminates about 3 x 10^13 microbes daily |
| normal flora of genourinary tract | upper (kidney, ureters and urinary bladder) should not have microbes |
| normal flora of respiratory system | upper (nasopharynx, oral cavity, larynx and pharynx) have a restricted number of colonies; lower (trachea, bronchi, bronchioles, and alveoli) should not have bacteria |
| normal flora of epithelium cells | mucous traps move microbes up and out via cilia and excreted in saliva and nasal secretions; finally, bactericidal effect of lysozyme |
| portals of entry of microorganisms | food and water borne; exhalation droplets (coughing and sneezing onto dust particles); direct contact (sexual); indirect contact (hand to hand or hand to eye); animal bites or scratches; parenteral (wound or puncture); vector transmitted |
| adherence (I) | bacteria or viruses usually initiate infection by adhering specially to epithelial cells through interactions (fimbriae) between macromolecules on surfaces of the pathogen and host; often begin at sites in mucous membranes |
| tissue selective | microorganisms adhere to specific receptors on specific cells |
| host selectivity | a microorganism that normally infects humans binds to human epithelial cells better than those of a rat |
| capsules, glycocalyx, or slime layer | may be involved in adherence |
| fimbriae and pili | bacterial surface protein structures that also function in attachment (bind to host cell glycoproteins or complex lipids); |
| adherence (II) | microbe may penetrate through small breaks or lesions or even an intact mucosal surface |
| invasion (III) | invasion, especially if normal flora is altered, then microbe may establish itself, grow, and multiply. |
| colonization and growth (IV) | production of virulence factors and either produce toxin effects (local or systematic) or further growth that ultimately leads to tissue damage and disease |
| invasiveness | grow in large numbers and may spread throughout host body |
| toxigenicity | toxins that inhibit host cell function or kill host cells (endotoxins and exotoxins) |
| humoral immunity (acquired or induced immunity) | mediated by antibodies |
| cellular immunity (acquired or induced immunity) | mediated by cells (T cells) |
| natural resistance or innate immunity | cells: macrophages; mechanical barriers: skin and mucous membranes; chemical factors: interferon, fatty acids on skin; microbial factors: normal florida competition |
| hyaluronidase | also called the spreading factor because it catalyzes the breakdown of hyaluronic acid, the substance that cements the human cells together; allows bacteria cells to spread through tissue causing cellulitis. |
| coagulase | catalyzes the conversion of fibrinogen to fibrin with the result being clot formation; present in pathogenic staphylococcus; allows bacteria to grow inside of the clot |
| fibrinolysin | catalyzes the conversion of plasminogen to the fibrinolytic enzyme plasmin; opposite of coagulase; allows the clot to dissolve and therefore spreading the bacteria |
| lipase | allows bacteria to penetrate fatty tissue with the consequent formation of abscesses |
| collagenase | catalyzes the degradation of collagen, a protein found in tendons, hair, and nails. |
| leukocidins | causes lysis of white blood cells; staphylococcus aureus |
| streptokinase and streptodornase | fibrinolytic enzymes |
| lecithinase | destroys red blood cells and other tissue cells |
| hemolysins | lyses red blood cells |
| Group A Streptococci (GAS) | enzymes to breakdown clots; enzymes to inhibit clotting machinery |
| clostridium perfringens | hyaluronidase and collagenase; food poisoning |
| gas gangrene | death and putrefaction of tissues, bubbles of gas in decomposing tissue; widespread and destroys tissue |
| LD50 | the dose of an agent that kills 50% of the animals in a test group |
| exotoxins | proteins secreted by certain g+ or g- bacteria; often highly toxic, sometimes fatal; generally heat-liable; highly immunogenic (stimulates production of antibodies) |
| endotoxins | part of the LPS layer in g- bacteria that are released when the cell lyses; extremely heat stable; weakly toxic, rarely fatal; relatively poor immunogen; causes fever |
| pyrogenic | induces fever in host |
| pyogenic | induces pus formation |
| cytolytic exotoxins | damages cell membranes, causing cell lysis and death |
| A-B exotoxins | B promotes specific binding of toxin to host cell receptor to allow transfer of the toxic part, A, across the targeted cell membrane |
| superantigen exotoxins | stimulate large numbers of immune lymphocytes and causes systemic as well as inflammatory responses; extensive inflammation and tissue damage; |
| cytotoxins exotoxins | inhibit a cell function or cause cell death |
| neurotoxins exotoxins | inhibit nerve transmission |
| enterotoxins exotoxins | alter permeability of intestinal epithelium and then causes massive secretion of fluid into the intestinal lumen causing diarrhea |
| alpha toxin | a pore forming cytotoxin that is produced by growing stapylococcal cells; released a monomer with 7 subunits; pore releases the contents of the cell while bringing in extracellular material; causes cell to swell and lyse |
| anthrax | made of three parts where each individual anthrax toxin protein is in fact, nontoxic. |
Created by:
JacobGant
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