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42 Cards in this Set
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Autoinducer |
Chemical signal molecules that enable bacteria to communcate |
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Quorum Sensing |
Allows bacteria to distinguish between low and high cell population density and control gene expression in response to cell number Related behaviors: symbiosis, virulence, antiobiotic production, and biofilm formation |
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Peptidoglycan |
Peptide cross-sections Glycan chains |
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Penicillin |
Binds and blocs transeptidase that cross-links glycan chains |
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4 Cell Wall Groups |
Gram positive cells Gram negative cells Bacteria without cell walls -- mycoplasma Bacteria with chemically unique cell walls--mycobacteria and nocardia |
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Gram Positive |
Thick, homogenous sheeath of peptidoglycan (20-80nm) Tightly bond, acidic, retain crystal violet and purple stain in Gram stain 1 layer-more permeable Narrow periplasmic space |
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Gram Negative |
Lipopolysaccharide and porins make up outer membrane--barriers to antibiotics, digestive enzymes, detergents, heavy metals; lipoproteins Thin peptidoglycan shell (1-3nm) Lose crystal violet stain and stain red from safranin counterstain in Gram stain 2 layers Extensive periplasmic space |
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Lipopolysaccharide (Gram Negative) |
Polysaccharide (sugar)-antigens Lipid A (endotoxin)-toxic when in host's blood stream Porins: proteins form channels; regulatory control over molecules entering and leaving the cell |
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Serotype |
A group of microorganisms distinguished by their shared specific antigens as determined by serologic testing (E. coli) |
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Pseudomurein |
Composes the cell walls of some archae and resembles the cell walls of Bacteria. Others have a surface layer |
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Prokaryotic Cell Membrane Functions |
Site for enery rections (ETC)--no mitochondria in prokaryotes Regulate transport Site or secretion |
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Cytosol |
Liquid portion of cytoplasm |
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Fertility (F) Factors |
Carry instructions for conjugation; includes genes for sex pillus |
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Resistance (R) Factors |
Carry genes for resistance to one or more antimicrobial drugs &/or toxic heavy metals |
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Bacteriocin Factors |
carry genes for proteinaceous toxins which kill closely related bacterial cells (competitors) without the factor |
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Virulence Factors |
carry genes for enzymes or toxins that enable bacterium to be pathogenic |
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Clostridum tetani |
Encodes tetanus toxin Stops affected neurons from releasing inhibitory neurotransmitters--failure to inhibit motor reflexes from smallest stimulus--uncontrolled muscle contractions Life threatening muscle spasms |
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E. coli O157 |
Possesses integrated virus (prophage) that encodes Shiga toxin Causes local areas of erosion in intestine Undercooked beef--foodborne pathogen |
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Prokaryotic Ribosomes |
large (50S) subunit and small (30S) subunit = 70S subunitSite of protein synthesis Gives cytoplasm graiiny appearance |
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Baterial Actin |
helps stabilize shape during cell enlargement and influences cell wall formation |
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Inclusions & Granules |
Storage bodies produced during periods of nutrient abundance Not bounded by embrane; substances compacted densly and do not easily dissolve into cytoplasmGlycogen, poly-beta-hydroxybutyrate, gas vesicles in protein sacs for buoyancy and flotation, sulfure, and polyphosphate granules (volutin) |
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Endospores |
Resting, inert, dormant body 1 of two phases in bacterial life cycle (vegetative and endospore) Hardiest of all life forms (25-250 million years) Not a means of reproduction Heat resistance -- high levels of calcium dipicolinic acid which removes water and stabilizes proteins and DNA cortex and spore coats protects against radiation, chemicals, heat, drying, and freezing Autoclave: pressurized steam at 120C for 20-30 minutes will destroy; not ordinarily boiling at 100C |
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Sporulation |
Formation of endospores (6-12 hours) |
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Germination |
return to vegetative growth |
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3 Shapes of Bacteria |
Cocci--spherical Bacilli--rod (cylindrical) Spiral (curviform)--rigid helix (spirillum with polar flagella), flexible helix (spirochete with periplasmic flagella) |
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Prokaryotic Cell Arrangement |
Planes in which cells divide Whether or not daughter cells separate completely or remain attached to each other Bacilli only divide in transverse plane (perp to axis) |
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Rickettsia |
Gram negativePathogens that alternate between mammals and vector blood-sucking arthropods Obligate intracellular pathogens Energy parasite Attach to endothelial cells cells and enter by rickettsia-induced phagocytosis--phagosome membrane lost and rickettsia escape into cytoplasm Pathological effects: vascular infiltration of inflammatory cells, vasculitis, Vascular leakage Thrombosis Manifested by: skin rash, edema, hypotension, gangrene |
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Coxiella burnetii |
Causes Q fever--flu like symptoms. self-limiting disease morphologically simialr to Rickettsia small gram negative coccobacillus bacterium intracellular parasite produces unusual type of sporeSpreads to humans by ingestion of unpasturized milk and inhaling aerosols in dairy barns acidophilic (4.5-5pH) free spore survives outside of host |
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Chlamydia |
gram negative coccoid bacteria obligate intracellular parasites not transmitted through arthropods Alternates between two distinct stages: small metabolically inactive state which is the infections form (elementry body), nd larger noninfectious form where it is actively dividing to form a reticulate body that grows within host cell vacuoles Human strains: Trachoma strain attacks the squamous or columnar cells of mucous membranes in the eyes, genitourinary tract, and lungs, and the Lymphogranuloma venereum strain--invades lymphatic tisues of genetalia |
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Lymphogranuloma venereum |
Chlamydia trachomatis infects lymph nodes and lymphatics |
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Mycoplasma pnemoniae |
Atypical pnemonia--walking pnemonia |
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Mycoplasma genitalium |
small parasitic bacteria that lives on epithelial cells of primate genital and respiratory tracts smallest known genome that can constitute a cell: 525 genes |
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Proteobacteria |
Gram negative cell walls |
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Firmicutes |
Gram positive cell walls with low G+C content & includes mycoplasmas |
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Actinobacteria |
Gram positive cell walls with high G+C content |
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Prokaryotic Flagellum |
Filament-- long, thin, helical structure composed of a single type of protein (flagellin) Hook-- curved; flexible coupling Basal body-- stack of rings firmly anchored in cell wall and cytoplasmic membrne; anchors hook; microscopic rotary motor to rotte hook and filament Rotates 360 degrees 1 or 2 distributed throughout cell surface |
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Prokaryotic Flagellar Arrangements |
Polar-- flagella attached at one or both ends monotrichous- single flagellum at one end lophotrichous-- small bunches arising from same site at one or both ends of the cell amphitrichous-- single flagellum at both ends of cell Peritrichous-- flagella dispersed randomly over surface of cell, slowest All rilla, half bacilli, and small number of cocci are flagellated |
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Flagellar Motion |
Counterclockwise--run Clockwise--tumble |
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Periplasmic Flagella |
Internal flagella enclosed in space between cell wall peptidoglycan and outer sheath of spirochetes Curl closely around the spirochete coils Snake/Worm-like motion to the cell |
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Fimbriae |
Fine hairlike bristles from cell surface of many gram negative and some gram positive bacteria Role in adhesion to other cells and surfaces Contribute to pathogenicity of certain bacteria by enhancing colonization on surfaces of cells of other organisms No locomotion |
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Pili |
Rigid tubular structure made of pilin found on gram negative cell intermediate length between fimbriae and flagella Joins bacterial cells for (partial) DNA transfer in a mating process (not sexual reproduction) termed conjugation |
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Glycocalyx |
Coating of molecules to protect a cell Functions: protects, attaches, inhibits killing by white blood cells 2 Types: Capsule-- highly organized, tightly attached to surface, and gives mucoid character to colonies Slime layer-- loosely organized and more loosely attached than capsule; easily washed off' protects from loss of H2O and nutrients |
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