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61 Cards in this Set
- Front
- Back
short, thin, hairlike, proteinaceous appendages; mediate attachment to surfaces
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fimbria
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similar to fimbriae except longer, thicker, and less numerous , required for mating
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sex pilus
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orderly arrangement of bacteria into groups
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Classification
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practical use of classification criteria to distinguish certain bacteria from others
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identification
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means by which characteristics of a species are defined and communicated among microbiologists
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nomenclature (naming)
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3 major categories of bacteria based on structures from cytoplasmic membrane to cell surface
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Gram positive, Gram negative, Acid-Fast
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Which type of bacteria have the thickest cell envelopes?
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Gram positive
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H-antigens
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prokaryotic flagella responsible for bacterial motility
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Functions of Bacterial Capsules
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Increases resistance to phagocytosis
Structure for cell attachment-tissue tropism Potential source of growth substrates |
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LPS is unique to what type of bacteria?
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Gram negative
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teichoic acids are unique to what type of bacteria?
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Gram positive
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Outer membrane of gram neg bacteria contains
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LPS, porins, lipoprotein (small molecules can move easily through porins)
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Inner/Cytoplasmic membrane of gram neg bacteria characteristics
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Composed of phospholipids, not permeable to ions, contain nutrient transporters, electron transport chain, and biosynthetic enzymes for peptidoglycan and LPS biosynthesis
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What is the "active" component of LPS?
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Lipid A
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Components of LPS?
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O-antigen (variable), polysachharides, Lipid A(invariable)
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Structure of peptidoglycans
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Two alternating sugars for the backbone: N-acetylglucosamine, N-acetylmuramic acid
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The gram stain procedure: is it useful for acid-fast bacteria?
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No
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Stages of peptidoglycan biosynthesis (3)
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Stage 1: Precursors synthesized in cytoplasm
Stage 2: Precursors transported across the cytoplasmic membrane bound to lipid carrier Stage 3: Precursors are polymerized and cross-linked to form a macromolecular sheet |
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What antibiotics inhibit stage 1 of peptidoglycan synthesis?
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Fosfomycin and Cycloserine
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PEP analog, inhibits UDP-muramic acid biosynthesis
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Fosfomycin
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Analog of D-alanine, competiviely inhibits conversion of L Alanine to D Alanine and synthesis of D Alanine D Alanine.
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Cycloserine
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During what stage is N-acetylmuramic acid linked to N-acetylglucosamine transported across the cytoplasmic membrane linked to lipid carrier?
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Stage 2
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Mech of action of vancomycin and ristocetin
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Bind to D-Alanine-D-Alanine structure and prevent transfer to acceptor. (Inhibit Stage 2)
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Mech of action of bacitracin
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Inhibits dephosphorylation of lipid carrier by binding to pyrophosphate (Inhibit Stage 2)
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During what stage is cross-linking of parallel polymers of N-acetylmuramic acid and N-acetylglucosamine ?
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Stage 3
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What happens to cross link N-acetylmuramic acid and N-acetylglucosamine?
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Terminal D-alanine is cleaved during transpeptidation which links the third amino acid to the remaining D alanine
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Mech of action of penicillin and cephalosporin antibiotics
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Inhibits Step 3 (cross linking)
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What is the reactive site of penicillin? Significance of this?
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peptide bond of beta lactam ring. It resembles the conformation of the transition state of alanine linkup in transpeptidation reaction
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What part of LPS provides protection from host defenses ?
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O antigen
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What part of LPS contributes to negative charge on cell surface?
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core polysaccharide
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What part of LPS helps stabilize outer membrane structure?
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lipid A
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What part of LPS can act as an endotoxin?
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lipid A
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In the gram reaction, what kind of bacteria retains crystal violet dye and stains dark purple?
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Gram-positive
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In the gram reaction, what kind of bacteria can be decolorized to accept counterstain/safranin and stain red?
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Gram-neg
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Peptidoglycan layer thickest in _____
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gram-pos
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highly toxic part of acid-fast bacteria cell envelope
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mycolic acid
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Class of antibiotics that inhibits bacterial DNA gyrase
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Quinolones
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Antibiotic that inhibits transcription by binding to beta subunit of bacterial RNA polymerase
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rifampin
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Class of antibiotics that inhibit protein synthesis at the 30s ribosomal subunit
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Tetracyclines and aminoglycosides
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Antibiotics that inhibit the transpeptidase reaction by binding to 50S ribosomal subunit.
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Chloramphenical, erythromycin, and clindamycin
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Inhibits bacterial dihydrofolate reductase
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Trimethoprin
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What part of the bacterial cell envelope prevents removal of red dye/fuscin with acid?
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Cell wall bound mycolic acid/lipid
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T/F Bacteria synthesis tetrahydrofolate (THF) from scratch while humans must intake dihydrofolic acid
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t
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T/F Sulfa and trimethoprin have synergistic effects in that they inhibit the THF pathway in two places
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T
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what drugs inhibit folic acid biosynthesis by acting as competitive inhibitors of P-aminobenzoic acid?
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Sulfa
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What drugs inhibit bacterial (but not mammalian) dihydrofolate reductase?
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Trimethoprin
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Binds D-ala-D-ala and inhibits transfer of growing cell wall polymer
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Vancomycin
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Quinolones and Nalidixic acid inhibit ____________
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DNA replication (DNA gyrase)
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Rifampin inhibits __________
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DNA-dept RNA polymerase
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Erythromycin, Chloramphenicol, and Clindamycin inhibit ______________
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Protein synthesis through the 50S subunit
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Tetracycline, -mycins, and Amikacin inhibit ___________
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Protein synthesis through the 30S subunit
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Polymixins disrupt __________
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the structure of the bacterial cell membrane by interacting with its phospholipids.
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Trimethoprim and Sulfonamids inhibit ___________
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folic acid metabolism
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Cycloserine, vancomycin, bacitracin, fosfomycin, penicillin, cephalosporins, monobactams, carbapenems inhibit __________
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cell wall synthesis
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LPS is also know as _____
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endotoxin
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physical property of some bacteria referring to their resistance to decolorization by acids during staining procedures.
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acid fast
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Mycolic acids found in genera __________________
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Mycobacteria and Nocardia
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What is "cord factor?"
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Toxic, ether-extractable glycolipid in mycobacterium tuberculosis' cell envelopes. Composed of disaccharide threhalose in ester linkage to mycolic acids. Acid fast bacteria also contain cell wall bound mycolic acids
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Two genera of bacteria that sporulate
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Bacillus and Clostridium
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Characteristics of bacterial spores
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Highly resistant to heat, chemicals, UV light, and dessication
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What compound imparts the indestructibility of bacterial spores?
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calcium dipicolinic acid
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