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micro mid term
| Term | Definition |
|---|---|
| def of microorganism | all organisms too small to be seen clearly with the unaided eye(microscopic) |
| microscopic exception | helminths (parasitic worms) are macroscopic as adults, but their eggs and larvae are microscopic and diagnostic |
| acellular agents | viruses, prions, and viroids are acellular and lack structure all together |
| cellular organisms | prokaryotes(bacteria and archaea) traditionally defines by the absence of a membrane bound nucleus and organelles |
| global disease impact | respiratory tract infections(pneumonia, infleunza, etc) and the #1 cause of infectious disease death worldwide |
| normal flora/microbiome | mots microbes colonizing humans are non-pathogenic; many are mutualistic and essential fro health |
| pathogens | pathogens represent only a small minority of all microbial species |
| genetic engineering | manipulation of microbial genetics to produce human proteins (e.g. e coli engeneering to produce human insulin |
| bioremediation | use of microbes to clean up pollutants or detoxify heavy metals from contaminated sites |
| biotechnology | commercial and industrial applications using microbes (bread making, wastewater treatment, antibiotic production) |
| viral size and visualization | ultramicroscopic in size(measured in nm). require an electron microscope to visualize |
| core nature | obligate intracellular parasites containing either DNA or RNA (never both simultaneously) encased in a protein coat |
| capsid | protein shell surrounding the viral nucleic acid core |
| capsomeres | protein subunits that spontaneously assemble to form the capsid |
| icosahedral capsid | 20 sides figure with 12 evenly spaced corners(e.g. adenovirus) |
| helical capsid | cylindrical , ribbon like structure(e.g. tobacco mosaic virus |
| nucleocapsid | nucleic acid core and capsid protein shell |
| naked virus | contains only a nucleocapsid (lacks an outer lipid envelope). released from host cells via cell lysis |
| envelope virus | outer lipid membrane acquired during viral budding or exocytosis form the host cell membrane or endomembrane |
| viral spikes | glycoproteins protruding from the envelope or capsid; coded by viral genome; mediate docking / attachment to host cell receptors |
| positive-sense (+) RNA | single stranded RNA ready for immediate translation into proteins by host ribosomes |
| negative sense (-) RNA | rna that must first be transcribes into a complementary positive sense rna copy before translation can occur |
| replication sites | most DNA viruses replicate inside the host cell nucleus; most RNA miruses replicate in the cytoplasm |
| bacteriophages | viruses that specifically infect bacteria. use tail fibers to attach to host receptors |
| lysogeny | process where viral DNA integrates into host bacterial chromosome as a prophage |
| induction | activation of latent prophage to exit the bacterial chromosome abd enter the lytic cycle |
| oncoviruses | mammalian viruses cpaable of initiating tumors/cancer |
| latent viruses | persistent viruses that remain inactive inside the host cells and reactivate periodically (herpes simplex) |
| prions | infectious protein particles lacking nucleic acid(cause BSE, CJD, Kuru) |
| viroids | infectious, naked strands of pant rna lacking a capsid |
| distinguishing features | bacteria lack a nuclear membrane (dna in nucleoid) , lack membrane bound organelles, and do not wrap dna around standard eukarioutic histones |
| pleomorphism | variation in side and shape among cells of a single species |
| flagellum structure (3 parts) | filament, hook and basal body(anchors teh flagellum into the cell envelope) |
| monotrichous | flagellum at one pole |
| amphitrichous | flagella at both poles |
| lophotrichous | tuft of flagella emerging from a single site |
| peritrichous | flagella distributed over the entire cell surface |
| axial filaments(periplasmic flagella) | endoflagella enclosed within the periplasmic space of spirochetes, producing a flexing / celia-like motility |
| chemotaxis | movement of a cell in response to a chemical gradient (pos-toward, neg-away) |
| sex pili | rigid, tubular protein tubes used to transfer plasmid dna between bacterial cells during conjugation |
| fimbriae | small, hair like bristles used primarily for attachment to surfaces |
| capsule | protects bacteria from phagocytosis by host white blood cells(macrophages/neutrophils) |
| gram pos cell envelope | composed of 2 layers: thick peptidoglycan cell wall and cell membrane. contains teichoic adis and lipoteichoic acid |
| gram neg cell membrane | 3 layers: outer membrane(LPS), thin peptidoglycan cell wall, and inner cell membrane |
| acid-fast cell wall | genera mycobacterium and nocardia contain waxy mycolic acid in thei cell walls; stained and using the acid fast stain |
| lysozome | enzyme in saliva and tears that hydrolyzed bonds in peptidoglycan glycan chains, degrading the bacterial cell wall |
| cytoplasm and ribosomes | dense cytoplasm containing 70 s ribosomes(composed of rrna and protein); site of protein synthesis |
| plasmids | small, double stranded circular dna molecules containing non essential advantageous genes |
| inclusions | nutrient storage granules(glycogen, polyphosphate |
| endospores | dormant , highly resistant structures produces by bacillus and clostridium to protect genetic material during harsh environmental conditions. rich in calcium and dipicolinic acid |
| bright field | most widley used; shows stained or dark specimens against a bright background |
| dark field | brightly illuminated specimen against a black background; besdt for live, unstained cells |
| phase-contast | differentiates intracellular structures in live cells based on tissue/organelle density* |
| flourescence | uses uv light and flourescent dyes ; uses in diagnostics |
| scanning electron(SEM) | uses electron beam ; bombards whole metal-coated specimen; produces 3D surface views |
| transmission electron(TEM) | uses electron beam; transmits electons through unltra thin slices; reveals internal cellular ultrastructure |
| magnification formula | total mag= ocular lens power x objective lens power |
| immersion oil | prevents light loss due to refraction/scatter when using 100x objective lens |
| resolution limit | a microscope with a .2 micrometer limitof resolution can resolve structures .2 or larger |
| metric units | 1mm= 1000 micrometers |
| motility test | hanging drop preparation is best for observing live, unattached cell motility |
| gram stain procedure | -crystal violet(primary) -iodine(mordant) -alcohol/acetone(decolorizer) -safranin(counterstain) |
| acid fast stain | differential stain targeting mycolic acid in mycobacterium and nocardia |
| the 5 I's | innoculation, incubation, isolation, inspection, identification *infection is not one of them!! |
| isolation | streaking/ streak plate method is most effective and common technique |
| colony formation | a single colony arises froma single parent bacterial cell(colony formation unit-CFU), not multiple cells |
| agar | complex ploysaccharide extracted from red algae; provides a solid matrix for growth without being digested by most bacteria |
| defined vs complex media | chemically defines: exact chemical composition and concentration known complex media: contains at least 1 component that isnt chemically definable(blood, meat, yeast) |
| selective vs differential media | selective: contains agents that inhibit the growth of certain microbes while encouraging others differential: displays visible differences among colonies or in the medium(color changes) |
| enriched media | contains complex organic substances (blood, hemoglobin) required by fastidious pathogens |
| reducing media | contains chemical agents (thioglycolate) that absorb/remove oxygen ; used for anearobes |
| polymers | macromolecules made of repeating sub-unit monomers |
| carbohydrates | monosaccharides(glucose fructose ribose, etc) * glycogen and starch are polycaccharides |
| lipids | phospholipids are the major component of cell membranes(glycerol + 2 hydrophobic fatty acid tails+ hydrophilic phosphate head). saturated fats have single bonds, unsaturated have double |
| proteins | polymers of amino acids linked together by peptide bonds. amino acids are structural building blocks of enzymes |
| nucleic acids | nucleotides(adenine, gaunine, cytosine, thymine, uracil). adenine(purine) pairs with thymine/uracil(pyrimidine); guanine(purine) pairs with cytosine(pyrimidine) |
| ATP (adenosine triphosphate) | adeenine + ribose + 3 phosphates. cellular energy transfer molecule |
| 3 domains of life | bacteria, archaea, eukarya(carl woese and george fox) |
| binomial nomenclature | Genus + species epithet. only first is uppercase, both italisized |
| taxonomy | involves nomenclature, classification, and identification * does NOT involve common names |
| sterility | complete absense of all viable life forms, including bacterial endospores and viral particles |
| joseph lister | advocated for surgical antisepsis(disinfecting hand/air w phenol) |
| kary mullis | invented polyamerase chain reaction(PRC) to amplify DNA |
| prokaryotes | cell structure: unicellular nucleus: no nucleus(nucleoid) genetic material: circular DNA ribosomes: 70s membrane sterols: usually absent cell wall: peptidoglycan (most) size: 1-10 micrometers |
| eukaryotes | cell structure: uni or multi cellular nucleus: present(nuclear membrane) genetic material: linear DNA ribosomes:80s membrane sterols: present cell wall: chitin(fungi); cellulose(plants) size: 10-100 micrometers |
| viruses | cell structure: acellular nucleus: absent genetic material: DNA or RNA(never both) ribosomes: none membrane sterols: absent(except host lipid envelope) cell wall: none (protein capsid shell) size: 20-400 nanometers |
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