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53 Cards in this Set
- Front
- Back
what allows bacteria to have a high metabolic rate?
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high surface to volume ratio
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what limits bacteria metabolic rate?
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diffusion
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do prokaryotes have nuclei?
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no
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are prokaryotes haploid or diploid?
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haploid
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what is the biofilm made by dental bacteria made of? and why?
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polysaccarides; to allow bacteria to stick to teeth
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what color do gram pos bacteria stain and what is the stain called?
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purple; crystal violet
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what color do gram neg bacteria stain and what is the stain called?
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red; safranin
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what makes the gram pos bacteria different?
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thick cell wall made of murein and teichoid acids
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murein:
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glycan sugars cross linked to each other by peptides
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what can be used to remove the cell wall of gram pos bacteria?
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lysosyme
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what is the role of the cell wall in the survival of gram pos bacteria?
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allows stability of the cell in presence of hypo/hypertonic solution
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what makes gram neg bacteria different?
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outer membrane containing LPS; periplasm between inner mem and cell wall
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what are the 3 components of LPS?
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lipid A, sugar core and O antigen chain
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what is another term for lipid A?
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endotoxin
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what is the role of O antigen?
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excludes hydrophobic compounds like bile salts and antibiotics
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how do nutrients like B12 and Fe get across the outer membrane of gram neg?
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specific transporters
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what is the role of porin proteins in gram neg?
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allows passage of molecules of 600-700 daltons into cell while excluding hydrophobic molecules
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what exists in the periplasm?
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enzymes to break particles into digestible size, binding proteins, enzymes to inactivated antibiotics
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what color do acid-fast bacteria stain? what is the name of the stain?
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red; hot carbolfuchsin
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what is used as a counterstain in acid fast staining?
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methylene blue
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what is special about the cell wall of acid-fast bacteria?
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it's waxy due to long chain hydrocarbons and sugars
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what are the advantages and disadvantages of the waxy cell wall of acid-fast bacteria?
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advantages: impervious to chemicals and acids, avoids killing by WBCs…disadvantages: slow growth, place of attachment for infecting bacteriophages
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with what do the beta-lactams interfere?
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transpeptidation causing the formation of penicilloyl-enzyme complex instead of D-Ala-enzyme complex
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what is required for bacterialcidal action of beta-lactams?
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cell growth
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MOA of vancomycin
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inhibits addition of subunits to growing chain
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MOA of fosfomycin
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inhibits creation of NAM-UDP
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MOA of cycloserine
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inhibits creation of monometric units in cytoplasm
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MOA of bacitracin
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inhibits regeneration of lipid carrier
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what makes mycoplasms resistant to penicillins?
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lack of murein with no defined shape
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what makes antrax bacillus resistant to penicillins?
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tough protein layer (S-layer) on outside
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what occurs in group translocation?
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chemical altering of the molecule
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siderophores are required for the uptake of what?
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Fe
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where does oxidative metabolism take place?
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bacterial membrane
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what is the structure of bacteria genome?
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numerous tightly twisted supercoils make up a nucleoid
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what causes supercoiling of genome?
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DNA gyrase
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what causes relaxation of supercoils in genome?
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topoisomerase I
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what are the 3 stages of DNA replication in bacteria? and at what 2 stages do antibiotics work?
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initiation, elongation and termination; the first 2
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what causes regulation of DNA replication?
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frequency of initiation
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where does DNA replication begin?
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replicative origin
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MOA of metronidazole
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anaerobic bacteria partially reduces the drug which causes incorporation into its DNA which makes it unstable --> death
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MOA of nalidixic acid
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inhibits DNA gyrase --> death
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MOA of fluoroquinolones
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inhibits DNA gyrase and topoisomerase to cause double strand DNA breaks
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what is the principal biosynthetic activity of bacteria?
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protein synthesis
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MOA of rifampin
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binds free-floating RNA polymerase to inhibit transcription; bacteriostatic
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MOA of chloramphenicol and macrolides
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binds 50S subunit to block the formation of peptide bonds near tRNA binding sites to cause truncated ribosome cycles
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MOA of aminoglycosides
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enhances interaction between 50S and 30S subunits to cause an accumulation of 70S --> death due to inhibition of elongation
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MOA of tetracycline
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prevents addition of tRNA to the ribosome
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MOA of linezoid
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prevents creation of initiation complex
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allows bacteria to change pilin or flagella to avoid killing by Ab
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phase variation
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what movement of flagella causes straight swimming?
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association into a bundle and counterclockwise motion
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law of growth, Nt =
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Nt = No * e^kt
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CFU =
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# colonies * dilution factor
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what is the string of genes needed for enzyme production called?
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operon
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