Bacteria - 2

  • Created by: LBCW0502
  • Created on: 18-10-19 10:38
Describe features of membrane structures (1)
Fluid mosaic model. ~70% of proteins are integral (channels, transporters etc). Performs same functions as plasma membrane in eukaryotes, also site of electron transport and phosphorylation of ADP (final e- acceptors, O2, SO4 2-, NO3-, CO3 2-)
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Describe features of membrane structures (2)
Mesosome - invagination of plasma membrane, resembling vesicles or lamellae (may be artefact)
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Describe features of cytoplasmic matrix (1)
Cytoplasm (packed with ribosomes, proteins, DNA, lacks cytoskeleton). Nucleoid (irregularly shaped protein, visible micrographs, consists of supercoiled bacterial chromosome)
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Describe features of cytoplasmic matrix (2)
Plasmid (extra-chromosomal DNA often coding for antibiotic resistance factors). Inclusion bodies (granules of organic/inorganic materials, used for storage or osmoregulation, may be bound by protein or lipid membranes)
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Describe features of cytoplasmic matrix (3)
Nucleoid in cytoplasm, supercoiled bacterial chromosome (method to prevent replication, inhibit supercoiling), plasmid (extra chromosomal DNA, used to transfer resistance mechanism from organism to another, same type/different class)
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Describe features of the cell envelope for Gram positive and Gram negative bacteria (1)
Peptidoglycan wall prevents osmotic lysis. Extracellular digestion occurs, with no storage of enzymes. Gram -ve outer membrane is main permeability barrier (intrinsic resistance to antibiotics e.g. vancomycin)
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Describe features of the cell envelope for Gram positive and Gram negative bacteria (2)
Digestive enzymes stored in periplasmic space. Intrinsic resistance, e.g. vancomycin - prevents replication of peptidoglycan (not effective against Gram -ve)
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Describe features of the Gram positive envelope
Peptidoglycan consists of amino acids (L-alanine, D-glutamine, L-lysine, D-alanine, D-alanine). Pentaglycine bridge. N-acetylglucosamine, N-acetylmuramic acid. Matrix, cell wall elongation (cell wall - target for vancomycin, beta lactams)
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Describe features of the Gram negative envelope
Thin peptidoglycan layer (L-alanine, D-glutamic acid, meso-Diaminopimelic acid, D-alanine), porins (efflux pump/resistance mechanism to remove antibiotics), lipopolysaccharides).
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Describe features of lipidpolysaccharides (LPS) - 1
O antigen - species specific antigenic component (n = 1-40). Core polysaccharide - common to different LPS - genus/family specific. Lipid A - integral with outer membrane, little variation between species, toxicity (pyrogen, cause septic shock)
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Describe features of lipidpolysaccharides (LPS) - 2
Antibiotics target bacteria, exposure to lipid A after bacterial breakdown/released into circulation. Patient may feel worse after Gram +ve treatment (also seen in patients with Gram +ve prior to treatment, tachycardia, low BP)
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Describe features of the acid-fast bacteria cell envelope (1)
Acid fast stain - carbol fushin, acid alcohol, methylene blue. Can appear as purple dots after Gram staining. (Features of bacteria - glycolipids, mycolic acids, porin, arabinogalactan, peptidoglycan, plasma membrane). Myobacterium TB, M.leprae
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Describe features of the acid-fast bacteria cell envelope (2)
Strongly hydrophobic cell wall due to waxy mycolic acids. Allows survival within macrophages and other cells. Confers intrinsic resistance to antimicrobials
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Describe features of external components (1)
All bacteria secrete some kind of glycocalyx, outer viscous polysaccharide and polypeptide covering. Gelatinous material (if tightly bound to cell wall - capsule, loosely bound - slime layer)
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Describe features of external components (2)
Glycocalyx aids adhesion to environment/host to allow colony/biofilm formation. Glycocalyx also inhibits opsonisation
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Describe features of antibiotic spectra and target locations (1)
Aminoglycosides, fluoroquinolones (target pseudomonas, Gram + and gram - bacteria). Tetracyclines/sulphonamides/trimethoprim/chloramphenicol/fosfomycin/cycloserine (target Gram+/- bacteria). Oxazolidinones/fusidic acid/mupirocin/pleuromutilins
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Describe features of antibiotic spectra and target locations (2)
Rifamycin/novobiocin/macrolides/lincosamides (target Gram -ve bacteria)
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Describe features of antibiotic spectra and target locations (3)
Envelope targets - polymyxin (pseudomonas, Gram +ve bacteria), beta lactams (pseudomonas, Gram +/- bacteria), vancomycin and daptomycin (Gram -ve bacteria)
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Give an example of a macrolide
Clarithyromycin
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Give an example of a fluoroquinolone
Ciprofloxacin
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Describe other structures in prokaryotes (1)
Flagella (organ of bacterial motility, long protein filaments extending from cell envelope, molecular motor driven by proton motive force). Pili (fimbriae) - proteinaceous, hair-like projections from cell, involved in conjugation/plasmid transfer
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Describe other structures in prokaryotes (2)
Also involved in attachment to host epithelium
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Describe features of the flagella
May be present at the poles of cells (polar), singly or in tufts. Peritrichous flagella present all over cell. In spirochetes (Treponema pallidum), they form axial filaments within periplasmic space
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Describe features of bacterial spores (1)
Under conditions of environmental stress, dormant spores are formed by species of genera Bacillus and Clostridium. Spores are highly resistant dehydrated structures containing bacterial genome (may survive for centuries)
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Describe features of bacterial spores (2)
Vegetative cycle (growth and division). Polar division, stage II (asymmetric cell division). Stage III, engulfment. Stage IV, cortex. Stage V, spore coat. Stage VI/VII, maturation, cell lysis. Germination
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Describe features of bacterial spores (3)
E.g. C.difficile, diarrhoeal disease (pass through stool). Spores provide protection of organism against damage, prevent organism being killed. Spread of spores if there is a lack of hand hygiene
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Describe features of bacterial spores (4)
Spore forming organisms survive outside the body (weeks/months), spread infection. Spores released when cell is destroyed. Spores find environment for optimal activity. Reservoir for potential infection
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Describe features of bacterial spores (5)
In-between stage for active and dormant organism. Unsure if organism is cleared from the body/environment
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Other cards in this set

Card 2

Front

Describe features of membrane structures (2)

Back

Mesosome - invagination of plasma membrane, resembling vesicles or lamellae (may be artefact)

Card 3

Front

Describe features of cytoplasmic matrix (1)

Back

Preview of the front of card 3

Card 4

Front

Describe features of cytoplasmic matrix (2)

Back

Preview of the front of card 4

Card 5

Front

Describe features of cytoplasmic matrix (3)

Back

Preview of the front of card 5
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