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55 Cards in this Set
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- Back
16.1
immersion oil |
- used to increase the objective diameter
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16.2
stains |
- used to increase contrast
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16.3
Gram Stain |
- Gram + and Gram -
- differentiated by physical and chemical properties of the cell wall - Gram + retains a complex that gram - bacteria cannot - grame + = purple - grame - = pink |
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16.4
gram stain procedure |
- thin smear of bacteria is applied to a glass slide
- sample passed thru a flame to heat fix the bacteria #1 crystal violet added for about a minute, staining purple - water wash #2 iodine added to act as a mordant to form a complex with crystal violet - excess iodine is washed away with water #3 alcohol added, washed off in 10 sec, as a decolorizing agent. - alcohol remove crystal violet-iodine complex - gram + = purple - grame - = colorless #4 counterstaining with safarin: give gram - = pink |
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16.5
gram negative: |
- alcohol dissolves the lipid outer membrane and the complex is released
- decolorization causes gram - rods to appear colorless while grame + = purple |
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16.6
acid fast stain |
- used if Mycobacterium is the suspected agent
- boiling is not used anymore - counterstain is methylene blue - bacteria of interest will stain red while everything else is blue |
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16.7
mycobacterium cell wall: |
- very waxy and hydrophobic (lipid-rich)
- resist decolorization with the acid-alcohol and retain primary red stain from the carbolfuchsin |
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16.8
staphylococcus |
- G+ cocci
- grape-like clusters |
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16.9
streptococcus |
- G+ cocci in chains
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16.20
streptococcus pneumoniae |
G+ diplococci
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16.11
Corynebacterium (diphtheriae) |
- G+
- rods in shapes resembling 'chinese characters' |
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16.12
clostridium |
- G+
- boxcar/brickshape rods |
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16.13
gonorrhea in the male |
- G- biplococci within a PMC cell
- penile discharge |
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16.14
prokaryotic cytoplasmic membrane: |
- does not contain sterols (i.e. cholesterol)
- has cell wall (peptidoglycan) |
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16.15
adherence |
phili
fimbriae capsule |
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16.16
anti-complementary |
capsule, protease
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16.17
anti-phagocytic |
capsule, leukotoxins
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16.18
subvert humoral immunity |
Fc receptors, Ig proteases, endotoxin, cell wall components
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16.19
subvert cellular immunity |
superantigens
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16.20
vaccine antigens and antigens inducing hypersensitivity |
wall and secreted proteins
lipoproteins lipids carbohydrates |
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16.21
cell and tissue damage |
exotoxins e.g. Cytotoxins, neurotoxins, etc
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16.22
Capsule (K antigen) |
- the external to cell wall structure.
- present in both Gram + and Gram - - usually carbohydrate, but they can be protein |
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16.23
structures of capsules |
- discrete: as seen from negative-stained slides, where there is a distinct halo around each bacterium that did not take the dye
- some have a slime/glycocalyx structure |
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16.24
capsule of bacillus anthracis |
contains polyglutamic acid
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16.25
function of capsules |
- antigenically diverse
- anti-phagocytic - anti-complementary - contribute to adhesion - true virulence factor - if bacterium lacks its capsule, it loses its virulence |
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16.26
flagella |
- composed of flagellin helically arranged and are driven by a proton motive force.
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16.27
fimbriae and pili |
- fimbriae = Type 1 pili
- hair like protrusions composed of fimbrillin subunits - act as adhesins by way of lectin (protein that binds a sugar) or protein-protein interactions - at the tip of each fimbria is a receptor for a complimentary ligand on a host cell - antigenically variable - may choose to express or not express fimbriae and/or pili to change antigen types |
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16.28
phase variation |
- a mode of gene regulation which produces populations of bacteria containing a mixture of cells expressing fimbriae (phase ON) and cells not-expressing fimbriae (phase OFF)
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16.29
Type II pili |
- sex pili
- act in conjugation between gram negative bacteria - pilus will act as a 'lasso' to catch and 'reel in' a bacterium, and their walls fuse, genetic material is exchanged |
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16.30
prokaryotes that lack cell wall: |
- mycoplasma and ureaplasma
- their cytoplasmic membranes contain sterols, which help to strength the cytoplasmic membrane |
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16.31
Gram + cell wall: |
- same cytoplasmic membrane as Gram -
- simple - 1 thick layer of peptidoglycan - contain teichoic acid |
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16.32
Gram - cell wall: |
- peptidoglycan layer is reduced to a thin monolayer between a lipid bilayer.
- lipid content of the outer membrane of the bilayer is permeabilized by alcohol inthe gram stain - consists of an outer membrane and the periplasmic space containing the peptidoglycan. - lipoproteins link outer membrane to peptidoglycan - transmembrane protein (OmpA) stabilizes the outer membrane - amphilphilic (amphipathic) = porins: ring like structures that penetrate through the outer membrane, allowing protein transport. |
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16.33
peptidoglycan |
- a glycan chain backbone of the disaccharide N-acetylmuramic acid N-acetylglucosamine
- chains are linked by tetrapeptides attached to N-acetylmuramic acid, forming a 3-D lattice. - tetrapeptides consist of alternating L and D amino acids (D is non-biological -> very difficult to digest these cell walls) - 1st and 4th amino acids are alanine - 3rd amino acid is always a di-amino acid e.g., lysine, diaminopimelic acid, etc - adjuvant: smallest fragment is muramyldipepti de (MDP) - thick and undifferentiated. - 50% of dry weight of bacterium - amino acids of both the cross-linking and the stem polypeptides can be different: the taxonomy of these microorganisms |
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16.34
peptide bond crosslink: |
- found only in gram + cell walls
- gives 3D structure of the wall - in gram - wall D-alanine binds directly to the di-amino amio acid |
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16.35
lipoteichoic acids |
glycerophosphate polymers terminating in glycolipid anchored in the cytoplasmic membrane
- a lipopolysaccharide cf. LPS of Grame - bacteria - immunogenic, extend from the cytoplasmic membrane through the wall to the external environment - ancor wall to cytoplasmic membrane |
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16.36
teichoic acid |
- ribitol phosphate polymers covalently linked to peptidoglycan
- modified with sugars and/or amino acids - anchored in the wall but extend to the exterior - immunogenic - capture captions - stablilze wall |
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16.37
Periplasmic space (Gram -) |
- lies between the cytoplasmic membrane and outer membrane
- contains a single sheet of peptidoglycan; relatively few peptide bridges and no interpeptide bridges - embedded in a polysaccharide gel - contains hydrolytic enzymes (some of which contribute to virulence), sugar trasnport system, nutrient-binding proteins |
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16.38
outer membrane (gram -) |
- asymmetric lipid bilayer
- outer leaflet composed of: proteins: 60% lipopolysaccharide (LPS) 40% effective barrier - molecular sieve - attachment site for conjugation 0 contains determinants of pathogenesis - protects the peptidoglycan and periplasm |
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16.39
outer membrane proteins Omp) |
- porins - transmembrane pores
- lipoprotein - anchors O< tp peptidoglycan - transmembrane protein (OmpA) - stabilizes OM |
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16.40
lipopolysaccharide |
- most potent immunostimulatory molecule that is known
- B cell mitogen (non-specifically activate all B cells) - activate the complement cascade and inudce cytokine release from cells of IR - causes fever, shock and disseminated intravascular coagulation (DIC) (systemic blood coagulation) |
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16.41
LPS can be divided into three parts: |
lips A: toxic component of LPS. Lipid A and the Core are important for the integrity of the OM. Thi sis necessary for the viability of the cell
Core- most of the core is essential for cell viability O antigen - it is attached to the core and extends perpendicularly away from bacterium surface. Not involved in virulence. Some gram - bacteria lack the O antigen |
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16.42
cytoplasmic membrane |
- most lack sterols (except Mycoplasma and Ureaplasma)
- take care of many of the functions of eukaryotic cytoplasmic organelles, such as electron trasnport and energy production, nutrient uptake and waste excretion. - ion pumps maintain the membrane potential and the CM is responsible for biosynthesis - site of attachment for flagella, pili and fimbriae. - antibiotics that act on the CM tend to act by disrupting the membrane and increasing permeability (e.g.. Bacitracin, Polymixcins) |
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16.43
Nucleoid |
- occupied by a circular, single molecule of helical dsDNA that is supercoiled.
- chromosome is around 1000um long and contains as many as 3500 genes - e.coli = 2-3um in length, has a chromosome 1400 um |
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16.44
Extrachromosomal DNA plasmids |
- independent, circular, double-stranded self-replicating DNA molecules that carry only a few genes
- plasmid genes are non-essential but confer a selective advantage, eg. encode antibiotic resistance, toxin production, unique substrate metabolism - regularly transmissible between bacteria of the same and different species and genera. (Enterococci are vancomycin resistant. Vancomycin used to be used as a last resort for staph infections, b/c staph is resistant to a lot of antibiotics. However, due to transmission of the antibiotic resistance gene, staph is now also resistant to vancomycin. |
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16.45
binary fission |
- how bacterium replicates
- occur every 20 mintues under facorable conditions - does not last long |
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16.46
antibiotics acting on nucleic acid: |
- antibiotics that disrupt DNA synthesis: metronidazole,
- inhibition of DNA gyrases or topoisomerases: quinolones, nalidixic acid - inhibition of DNA dependent RNA polymerase: rifampin, rifabutin |
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16.47
ribosomes |
30S + 50S subunits = 70S ribosome
- proteins and RNA in the prokaryotic ribosome are different to eukaryotic ribosomes |
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16.48
antibiotics acting on protein synthesis |
- irreversible or reversible binding to 30S ribosomal proteins: Aminoglycosides, tetracyclines
- reversible binding to the 50S subunit: chloramphenicol, macrolides, lindamycin, streptogramins |
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16.49
inclusion granules |
- polyphosphate metachromatic (volutin: food stores in the cytoplasm)
- glycogen/starch - lipid - marker in identifying bacteria (responds to iodine stain). |
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16.50
k. spores |
- gram + rods only
- in bad environment, bacteria produce spores. cells start out as vegetative cells, environmental trigger => binary fission. - one daughter nucleoid will be enclosed in a double cell membrane and double cell wall containing only essential biochemical proteins and DNA. - the cell disrupt and the spore will be released while the other daughter cell dies. |
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16.51
biothreat agents |
- bacteria than can sporulate are considered biothreat agents
- there are readily aerosolized and are able to survive for a long time wherever they land. - weaponsized spores have outer charges removed -> airborne longer - spores are resistant to radiation and other chemical and physical means of disinfection. |
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16.52
clostridium tetani |
- biothreat agents
- microscopic morphology unique in that the spores are located atht epole of the bacterium cell, giving it a 'tennis racket' appearance - obligate anaerobe - toxins released target the CNS and periphearl nerve ends and bind irreversibly - leads to unopposed muscle contraction |
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16.53
Clostridium botulinum |
- a muscle relaxant (why botox is used)
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16.54
bacillus anthracis |
- spores of B. anthracis are in the middle of the cell and do not bulge out
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16.55
opportunistic pathogens |
- sporulating bacteria are usually opportunistic pathogens
- saprophytic, or soil-living, and survive as spores when there isn't enough nutrients - when the environment is favorable again, they resturn to vegetative cells. - transformation from a vegetative cell to a spore and vice versa will release toxins in the process, making the environment dangerous for us |