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77 Cards in this Set
- Front
- Back
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Prokaryotic Characteristics
1 - Genomic 2 - Gene Expression Reg 3 - Transcription 4 - mRNA translation |
1 - Single Chromosome, Haploid, single gene copies, precise colinearity with mRNA
2 - Mostly transcriptional, Operon-polycistronic mRNA 3 - Couple with translation, little mRNA processing 4 - first AA is formylated methionine, three initiation factors, and a 50S+30S=70S ribosome structure |
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Eukaryotic Characteristics
1 - Genomic 2 - Gene Expression Reg 3 - Transcription 4 - mRNA translation |
1 - single gene copies with non-coding regions, diploid+haploid structures, intron removal before mRNA
2 - Posttranscriptional regulation by protein turn-over, single genes at a time 3 - not coupled with translation 4 - first AA is methionine, six initiation factors, 40S+60S=80S |
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# of bacteria in GI tract?
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10-100 Trillion
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Why are microbes allowed high metabolic rates?
-example/indicator? |
small size leads to large SA/Volume ratios, greatly increasing diffusion capability
only 1% of bacterial dry weight is building blocks, rapid use |
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20x ^ in what component of gram+ vs Gram- CW?
structure? function? |
Murien
alt. N-acetylmuramic and N-acetylglucosamine acids with peptide chains. The peptide cross-link other chains Protection of the cell. For example in hypo-osmotic media. Also supplied structure to bacteria. Hydrophilicity of the AAs prevents entry of hydrophobics |
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Four Steps of Gram Stain?
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1 - Crystal Violet
2 - Potassium Iodide 3 - Alcohol (only + remain purple) 4 - Sarafin (Gram-'s go pink) |
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Three Steps of Acid-Fast?
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1 - Strain with *hot carbolfuchsin(red)
2 - Acid Alcohol (only acid-fast remain red) 3 - Methylene Blue counterstain |
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Structure of Teichoic Acid?
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Ribitol or glycerol linked by phosphodiester bonds
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Difference of gram+ and gram- murien cross-linking?
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Gram(+) goes Lysine to D-alanine carboxyl group
Gram(-) is DAP to D-alanine |
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Formation of a spheroblasts?
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Administration of lysozyme to gram(+) cells and then placement in a isotonic environment
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Struct/Fxn Lipid A
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disaccharides linked to FAs and phosphate groups
FAs provide hydrophobicity |
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Struct/Fxn Core (of LPS)
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Ketodeoxyoctanoic acid and heptose
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Struct/Fxn O Antigen
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Carbohydrate chains of up to 40 sugars
*Antigenic Specificity* Resistance to Hydrophobic compounds |
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transport of hydro-phobic/philics through gram(-) outer membrane?
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Porins allow travel of small hydrophilics (AAs, sugars, ions) but reject hydrophobics large or small
Large essential hydrophilics like B12 and Iron use specific transport proteins |
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Periplasm - Location, Structure, Function
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Located between CW and IM, is gel-like and contains murien. Contains enzymes to break down large macronutrients, enzymes to to inactivate anti-biotics, and large proteins for uptake of sugars/AAs
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Which component of the gram(-) outer membrane is immune reactive?
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Lipid A (endotoxin) - ellicits powerful immune reaction
The O-Antigen is highly antigenic |
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waxes?
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long hydrocarbons with murein, polysaccs, and lipids. proctective against many acids and chemicals but slows the life cycle greatly (TB - 24hrs)
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Vancomycin mech?
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Inhibits addition of disaccharides ot growing murein chain
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Bacitracin mech?
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inhibits lipid carrier regeneration during murien transport from cyto to periplasm
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Why is penicillin effective is shutting down transpepsidation?
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its strong stereochemical similarity to d-ala-d-ala. confusion arises and results in production of a lethal compound. As the cell continues to produce murien constituents it swells to death
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Why is it not wise to administer a growth stopping antibiotic with penicillins?
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penicillins cause death by allowing growth without gain in function
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Tolerance to penicillins?
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a defect in autolysin which allows for its increased activity, allowing slower lysis instead of explosion
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Why are mycoplasmas resistant to penicillin?
Anthrax? |
They lack a cell wall and their membranes constist of sterols instead of murien
Anthrax has an additional exterior S layer |
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Facilitated diffusion?
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does not concentrate compounds, relies on intracellular use of compound to allow more to enter
no E |
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Group Translocation?
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E dependent phosphorylation mechanism (gluc-->g-6-p)
SUGARS |
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Active Transport
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Transport coupling system
H+ and X (ATP/NADH proton) Energy dependent Entrance of molecules (ex LACTOSE) without modification Most widely used |
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Iron Uptake
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SIDEROPHORES bind with high avidity and specifically for their bacterial type
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Bacterial DNA Structure?
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Nucleoid formed into supercoils, wound by DNA gyrase and unwound by Topoisomerase1
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How is chrom. replication regulated in bacteria?
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by the frequency of initation, which is determined by the cells rate of division
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What is and Why is metronidazole not dangerous to humans?
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a DNA replication inhibitor which is only active when partially digested. This only occurs in anaerobic bacteria
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Why is it not wise to administer a growth stopping antibiotic with penicillins?
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penicillins cause death by allowing growth without gain in function
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Tolerance to penicillins?
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a defect in autolysin which allows for its increased activity, allowing slower lysis instead of explosion
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Why are mycoplasmas resistant to penicillin?
Anthrax? |
They lack a cell wall and their membranes constist of sterols instead of murien
Anthrax has an additional exterior S layer |
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Facilitated diffusion?
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does not concentrate compounds, relies on intracellular use of compound to allow more to enter
no E |
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Group Translocation?
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E dependent phosphorylation mechanism (gluc-->g-6-p)
SUGARS |
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Active Transport
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Transport coupling system
H+ and X (ATP/NADH proton) Energy dependent Entrance of molecules (ex LACTOSE) without modification Most widely used |
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Iron Uptake
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SIDEROPHORES bind with high avidity and specifically for their bacterial type
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Bacterial DNA Structure?
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Nucleoid formed into supercoils, wound by DNA gyrase and unwound by Topoisomerase1
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How is chrom. replication regulated in bacteria?
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by the frequency of initation, which is determined by the cells rate of division
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What is and Why is metronidazole not dangerous to humans? Mechanism of action?
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a DNA replication inhibitor which is only active when partially digested. This only occurs in anaerobic bacteria
Incorperates into DNA making it unstable |
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% dry weight proteins/RNA in bacteria
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40, 30
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What is the principal biosynthetic activity of rapidly growing bacteria?
How does this effect RNA production? |
Protein synthesis
RNA rate ~ RNA polymerase available Protein ~ Ribosomes |
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Rifampin
-Mechanism? -specific uses? -why human safe? |
binds FREE RNA polymerse, therefore targeting initiation specifically
TB and Leprosy Human RNA polym doesn't bind |
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B-Lactams - ex's + Action
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Penicillins, cephalosporins, carbapenems
inhib transpepsidation during CW murien synth, autolysis |
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Imidazoles - ex's + action
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-conazole's
-block synth of ergosterol in fungal CW |
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Echinocandins -ex's + action
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caspofungin, mycofungin
block B-glucan synth in fungal CWs |
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Daptomycin - type + action
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lipopeptide AB
forms channels in G+ CMs > K+ leakage > death |
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Amphotericin B - type + action
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Polyene
Bind to sterols in Eukaryotic CMs > leakiness > lysis |
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Sulfonamides - Action?
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Folate Antagonist
comp inhib of dihydropteroate synth, block synth of FH4 |
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Trimethoprim
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Inhib bacterial dihydrofolate reductase
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Aminoglycosides - ex's + action
-less effective vs? |
gentamicin, tobramycin, streptomycin
Bacteriocidal Bind 30s (form 70s), inhib @ elongation and kill by blocking INITIATION irreversible less fx anaerobes |
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Macrolides - ex's + action
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erythromycin, azithromycin, clindamycin
bind 50S and inhib @ ELONGATION step Bacteriostatic |
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Fluoroquinolones - ex's + action
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-floxacins
inhib action of DNA gyrase and topoisomerase causing dsDNA breaks |
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Capsule components? Appearance on agar?
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high MW polysaccharides
viscous and shiny (non appear small and dull) |
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Linezolid - action
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blocks assembly of initation complex
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Tetracycline
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inhibits aminoacyl transfer RNA binding
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Swimming:Tumbling ratio changes
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no chemo - equal
chemoattractant - S>T Repellant - S<T |
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What gives bacteria the ability to conjugate? What is the structure/fxn
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F or Sex Pili
Longer, give ability to xfer DNA |
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Gonococci Pili?
similar examples of adaptation? |
Controlled by Pilin protein, constant and variable regions (antigenic aspect) which can transform constantly
Relapsing Fever (Boriella) Sleeping Sickness (Trypanosomes) Salmonella (flagellated/non) = phase variation |
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What are the two main groups based on nutritional requirements? Where do pathogens lie?
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the photo/chemo-synthetics which can sustain off CO2 and minerals
organisms that need preformed organic compounds all lie in the second group |
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Strict Aerobe ex
Strict Anaerobe ex Facultative anaerobe ex |
TB
Botulism/Tetanus E.Coli |
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What is the electron acceptor in lactic acid fermentation? Ethanol?
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Pyruvate --> Lactate
ACoA --> Alcohol |
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Why is pseudomonas omnipresent?
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can use 100s of molecules for energy
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What does minimal media consist of?
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Water Glucose Ammonia Phosphate Sulfate +Minerals
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What does Nutrient Broth consist of?
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meat extract, soluble partial hydrolysates of complex proteins
+agar --> solid medias |
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Nutritionally Fastidious indicates?
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likely can only grow on human host
strep/staph |
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Total Count
-measured by? -indicates? |
hemocytometers, e- particle detectors
measures soley as physical particles, not as living or viable |
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Colony Count
-measures? -considerations? |
measures living or viable cells by CFUs
if cells grow in clumps or chains (staph or strep) counts may be lower than reality |
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Stationary Phase
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Stage where growth stops, population begins to decrease, viable counts drop below total counts
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How do E.Coli survive stationary phase?
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Break down of turnover of cell material involved in unused pathways
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SOS Response
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DNA repair post-UV radiation
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Sporulation - mech + ex
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Lysis of mother cell producing a metabolically inert spore and releasing a large amount of toxins
ex - tetanus, gas gangrene |
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Parsimony
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not making thing you don't need, leads to efficiency
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How do prokaryotic cells turns off entire pathways simultaneously?
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Operons
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Attenuation
-common use -mechanism |
commonly used in AAs
when AA is available exogenously, the attenuator binds to the promoter region and ceases synthesis |
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Repressors
-common use -mechanism |
Commonly used in sugars
Repressors are inherently bound, when the digestive enzyme is needed, the sugar binds to the repressor and inhibits its inhibition |
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Why does regulation in bacteria work so quickly?
Energy Considerations? |
bacterial mRNA is short lived, and what enzymes remain undergo feedback inhibition
It must cost less energy to shut down a pathway than to leave it open |
