Term
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Definition
-Common Ancestor
-Bacteria
-Gram positive/negative
-Spirochetes
-Chlamydia
-Archaea (formerly called archaebacteria)
-No known pathogens (yet)
-Contains many extremophiles
Methanogens (obligate anaerobes) swamps, anaerobic ground water sources: Carbon derived from carbon dioxide or acetate
Extreme halophiles: Require high salt (3-5 M)
Extreme thermophiles: 55-100ºC
Some species present in digestive tract
Biochemically distinct from bacteria
No peptidoglycan
-Membrane chemistry different |
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Term
Typical bacterial diameter |
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Definition
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Term
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Definition
-Colony consistency and texture
-Dry, slimy (mucoid), buttery
-Smooth surface, wet, rough, granular
-Opaqueness
Pigment
-None(usually pathogen's color), red, yellow, orange, brown, green |
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Term
Relationship Between Colony Appearance and Cell Physiology |
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Definition
Colony appearance may give important clues about the identity of the organism
-Colony morphology does NOT relate to shape of individual bacteria
-Mucoid appearance often indicates capsule
-Waxy appearance indicates high lipid content- could be Mycobacterium
-Highly motile organisms often form thin, spread-out colonies
-Pigments are often a form of protection against light- indicates where organism normally lives |
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Term
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Definition
Definition :Consists of cell membrane(s), cell wall (if present), including imbedded proteins, and glycocalyx or capsule (if present)
Functions:
Barrier
-Osmotic protection
-Regulated environment (pH, solute gradients)
-Solute transport
-Electron Transport
-Electrochemical gradients/ATP synthesis
-Motility
-Lipid biosynthesis
-Protein Secretion
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Term
Gram Positive Cell Envelope |
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Definition
-Thickpeptidoglycan layer
-Teichoic and lipoteichoic acids
-Give cell wall a net negative charge
-Important for serotyping
-Can be shed and elicit host immune response |
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Term
Gram Negative Cell Envelope |
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Definition
Outer membrane limits access of penicillin
-Thin peptidoglycan layer
- Two Membranes
-Periplasmic space:
May contain virulence factors such as collagenase, hyaluronidase, b-lactamase |
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Term
Comparison of Eukaryotic vs Prokaryotic Membrane Lipids |
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Definition
-Eukaryotic membranes
-Phosphatidylcholine (PC)
-Contain sterols
-Prokaryotic
-Phosphatidylethanolamine (PE)
-Targeted by polymyxins
-Phosphatidylglycerol (PG)
-Cardiolipin
-Do not contain sterols, with the exception of mycoplasmas and Helicobacter
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Term
Molecules Commonly Requiring Active Transport |
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Definition
-Iron and other metals
-Ions (Na+, H+, etc.)
-Amino acids/ dipeptides
-Transporters specific for one or a small group of related amino acids
-Sugars
-Vitamins |
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Term
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Definition
-All organisms have efflux pumps
-Physiological roles (not completely understood)
-Extrusion of toxic metabolites
-Heavy metals
-Roles in pathogenesis
-Efflux of bile salts
-Up-regulated following phagocytosis
-Resistance to antimicrobial agents
-MDR organisms express high levels of efflux pump proteins
-Antibiotics, antiseptics, solvents, and detergents can be substrates
-Development of “helper drugs”
-Inhibition of efflux pumps renders bacteria susceptible to antibiotics |
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Term
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Definition
-The peptidoglycan layer is critical for resistance to osmotic stress
-Consists of:
amino acids (hence, “peptido-”)
sugars (“glycan”)
Other molecules may be inserted into this structure
-A very important target for antibiotics
-Has pyrogenic activity
Repeating structure with crosslinks gives rigidity
Structure is NOT impermeable, and permits diffusion
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Term
Properties of Peptidoglycan |
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Definition
-Usually only 1-3 layers thick in G-; Up to 10x thicker in G+
-Mechanical properties more similar to viscous gel than crystalline structure (i.e., it can stretch)
-Proteins <50 kDa can diffuse across PG, along with DNA, nutrients |
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Term
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Definition
-Gram positive organisms are most sensitive
-Lysozyme can cross the outer membrane of G- after osmotic shock and EDTA treatment |
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Term
Transpeptidation reaction inhibited by b-lactam antibiotics
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Definition
Penicillin binding proteins (PBP)-bacterial transpeptidases and carboxypeptidases which are inhibited by penicillin
-b-lactam ring resembles the transition state of D-alanyl-D-alanine which
occurs during transpeptidation reaction |
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