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53 Cards in this Set

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