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109 Cards in this Set
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- Back
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biofilm |
a community of bacteria that forms on surfaces of our body parts ex. plaque on teeth |
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biofilm complications |
biofilm makes it hard to treat bacterial infections as all the biofilm has to be scraped |
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Metabolism |
sum total of all chemical reactions within an organism |
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catabolic |
release energy |
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anabolic |
store energy |
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catabolism |
chemical reactions that release energy, breakdown of organic compounds |
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catabolism example |
glucose (C6-H12-O6) -> CO2 + H2O release of ATP ATP= energy |
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anabolism |
chemical reactions that require energy, building of complex organic molecules from simpler compounds (stores ATP) |
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anabolism example |
formation of polysaccharides from simple sugars like glycogen from glucose |
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Reaction rates |
temperature dependent, higher the temp, higher the reaction rate |
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reaction rates drawbacks of too high a temp |
high temp. may kills cells- denaturation of proteins |
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Enzymes and reactions |
Reaction rates can only be a certain temp b/c reactions occur in the body, enzymes help to catalyze these, so temp. needed ins't as much as what would be needed in outside environment |
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Enzymes |
Large protein molecules- biological catalysts Make chemical reactions happen 100 million faster |
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Enzymes- Substrates |
substrate specific have suffix "ase" |
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Enzymes and cofactors |
Enzymes may need cofactors, such as metal ions like zinc, magnesium |
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Enzymes and recycling |
Enzymes are recyclable, unchanged during reaction |
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Factors that affect enzymes temperature |
too high a temp. can denature enzymes |
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Factors that affect enzymes pH |
some enzymes only work at certain pH ranges |
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Factors that affect enzymes Saturation |
are there equal amounts of substrate and enzymes, is it efficient |
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Factors that affect enzymes Salt concentration |
salt can suppress water but enzymes need water to function |
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Factors that affect enzymes Inhibitors |
can inhibit the growth of bacteria. silver dressings can inhibit infections for burn patients |
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Energy for microbes |
most microbes use carbs as primary source for production of energy glucose is the most common nutrient source |
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Process by which glucose is used: |
cellular respiration -aerobic -anaerobic fermentation |
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glucose processes and glycolysis |
both cellular respiration and fermentation use glycolysis where the final product is pyruvate ex. Embden-Meyerhorf Pathway (produces ATP) |
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Aerobic respiration |
produces more ATP than anaerobic processes about 38 ATP from 1 glucose molecue |
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Aerobic bacteria growth |
aeriobic bacteria usually can grow faster b/c they can make more ATP about 38 ATP from 1 glucose molecue |
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obligate aerobes |
bacteria that need oxygen in order to grow |
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Anaerobic respiration |
Less ATP produced than aerobic respiration About 2-4 ATP |
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Anaerobic bacteria growth |
usually slower b/c of minimal ATP production |
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Obligate Anaerobes |
bacteria that can only grow w/o oxygen |
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Fermentation |
is an important biological process does not need O2 but can occur in presence of O2 produces small amounts of ATP b/c energy is not released in end product, it remains in bonds |
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Fermentation products |
1. Lactic Acid 2. CO2 3. alcohol 4. yogurt 5. yeast |
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Energy sources other than glucose Lipids (fats) |
broken down by lipases fatty acids and glycerol which enter Krebs Cycle after Krebs, ATP is produced |
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Energy sources other than glucose Protein |
broken down by proteases, ends up in Krebs cycle after Krebs, ATP is produced |
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Factors affecting bacterial growth physical factors: temperature psychrophiles |
cold loving -5 to +15 C wont cause too much infection |
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Factors affecting bacterial growth physical factors: temperature psychrotrophs |
20-30 C ex. listeria |
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Factors affecting bacterial growth physical factors: temperature mesophiles |
25-45 C most pathogens our body temo is 37 C, thus mesophiles will grow at the same temp as our bodies |
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Factors affecting bacterial growth physical factors: temperature thermophiles |
typically grow in hot springs; heat loving not animal harbouring 45-70 C |
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Factors affecting bacterial growth physical factors: temperature hyperthermophiles |
70-110 C |
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Listeria monocytogenes morphology |
gram + bacillus, non-spore forming |
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Listeria monocytogenes oxygen and growth |
facultatively anaerobic |
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facultatively anaerobic |
can grow with or w/o oxygen will grow on anything |
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Listeria monocytogenes is it motile |
Listeria monocytogenes is very motile |
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Listeria monocytogenes temp. range for growth |
3-42 C |
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Listeria monocytogenes pH range for growth |
greater than/equal 5.5-9.5 |
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Listeria monocytogenes salt concentration range for growth |
can grow in high concentrations of NaCl, up to 10% |
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Listeria monocytogenes Growth on BAP |
grows well on BAP |
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Listeria monocytogenes normal habitat |
widely distributed in nature, soil is probably the natural reservoir enter animal intestines through contaminated feed |
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Listeria monocytogenes hardiness |
survives in low temp., high acidity and salt concetrations |
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Listeria monocytogenes meat packaging |
listeria can easily contaminate areas that may com into contact with meat that will be packed |
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Listeria monocytogenes clinical presentation in animals |
-CNS infections - In goats and cattle, "circling disease" - Septic Abortion |
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Listeria monocytogenes clinical presentation in man |
-food borne disease -CNS infections/ death - abortion |
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Circling disease |
deterioration of CNS, making goats and cattle only walk in circles |
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Septic Abortion |
the spontaneous abortion of animals |
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Listeria monocytogenes pathogenesis-invasion |
ingestion of contaminated food invasion of bacteria through gastric epithelial barrier. has a protein (ActA) that changes the cytoskeleton of gastric wall to rocket itself, moving from cell to cell |
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Listeria monocytogenes pathogenesis style |
invasin |
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macrophages |
white blood cells that are really good at fighting bacteria, eating them up. |
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Listeria monocytogenes and macrophages |
Listeria can survive and grow i splenic and hepatic macrophages macrophages has a phagolysosome, where bacteria are exposed to certain enzymes and chemicals that eats up bacteria, Listeria counteracts this by destroying the phagosome before it becomes phagolysosome with listerolysin |
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Listeria monocytogenes destroying cell membranes |
aside from listerolysin, Listeria monocytogenes produces two other hemolysins |
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Listeria monocytogenes clinical infection |
meningitis encephalitis septicimia |
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Listeria monocytogenes locating |
hard to locate where Listeria is from b/c of the long incubation period. also, hard to catch symptoms |
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Listeria monocytogenes and Age |
if young and have good immunity, there is high chance for survival Not the same for oder people and immunocompromised people |
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Listeria monocytogenes mortality of CNS infection |
20-50% difficult to diagnose meningitis |
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Listeria monocytogenes pregnant women |
pregnant women are immunocompromised b/c immunsystem has to change b/c of proteins from fetus influenza-like bacteremic illness can result in abortion or stillbirth |
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Listeria monocytogenes transmission |
food ex. coleslaw, soft unpasteurized cheese, cold cuts, milk, mushrooms, prepackaged salads |
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epidemiology |
tracking bacteria and its causes |
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Listeria monocytogenes epidemiology |
hard to track b/c of long incubation period and underreporting |
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Listeria monocytogenes stats |
responsible for about 1700 invasive disease in the US yearly fatal 33% of cases even with proper treatment maple leaf 2008: 57 severe infections 23 deaths |
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bacterial growth-pH |
pH 5-8 for most human pathogens too high or too low pH can denature enzymes |
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bacterial growth- osmotic pressure |
balance of particle concentrations in and around cells |
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bacterial growth- osmotic pressure isotonic solution-flacid |
same concentrations in and around the cell |
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bacterial growth- osmotic pressure hypotonic solution- turgid |
fewer particles/ml in solution than inside of a cell water enters cell to even osmolality, causing cells to explode |
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bacterial growth- osmotic pressure hypertonic solution-plasmolyzed |
more particles/ ml in solution than in cell water leaves the inside of cell, causing the cell to dehydrate, cell membrane collapses. PLASMOLYSIS |
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PLASMOLYSIS and the food industry |
salt or sugar solution used to preserve food by shrinking cell walls that create energy, less bacterial growth |
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bacterial growth-gaseous requirements strict aerobe |
bacteria will only grow on surface of the oxygen as there is only oxygen available at the surface |
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bacterial growth-gaseous requirements facultative aerobe |
will grow on top as well as through out vial, as it can grow with or w/o oxygen |
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bacterial growth-gaseous requirements strict anaerobe |
no oxygen at all |
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bacterial growth-gaseous requirements microaerophile |
can grow with some oxygen but not as much as in the air. will grow in the vial with the gas |
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bacterial growth-gaseous requirements aerotolerant anaerobe |
can grow for a bit where there's some oxygen |
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left to right strict aerobe, facultative anaerobe, strict anaerobe, aerotolerant anaerobe, microaerophile |
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aerobe and anaerobe co-existance |
aerobes and anaerobes can coexist as aerobes will use up all oxygen and anaerobes can begin to grow |
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Bacterial growth Chemical factors |
sources of C,N,O,S,P and trace elements sources of organic growth factors, provide environments bacteria can grow in |
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bacterial growth: environmental factors intracellular growth intracellular organisms |
evade defence mechanisms (WBC) need to use antibiotics that penetrate host cell membranes in order to treat infection some can't be grown on artificial media, must be cultured in living cell culture dependant on host cell for energy, lack enzymes for atp production ex. Chlamydia |
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bacterial reproduction |
binary fission |
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bacterial reproduction generation time |
-time for on bacterium to divide into two -dependant on media and growth conditions -aerobic bacteria usually grow much faster than anaerobic bacteria (higher production of ATP) |
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which grows fastest? left to right mycobacterium tuberculosis, escherichia coli, mycobacterium leprae, treponoma pallidum, staphylococcus aereus |
Escherichia coli, staphylococcus aereus, mycobacterium tuberculosis, mycobacterium leprae, treponema pallidum |
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how do we express bacterial # |
using log expression ex. 1x 10^8 |
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bacterial growth kinetics- Lag Phase |
bacteria are trying to organize itself for growth |
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bacterial growth kinetics exponential phase |
growth is exponential as bacteria become ready. They are most susceptible to antibiotics at this time |
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bacterial growth kinetics stationary phase |
no more growth, bacteria start dying off maybe b/c they use up all their energy |
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bacterial growth kinetics death |
bacteria start to slowly die |
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biofilms |
bacteria like to live in communities |
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peercentage of human infection that involves biofilms |
85+ |
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biofilm dynamics |
bacteria aren't stuck in biofilm, they can leave and start a new focus of infection |
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biofilm make up |
slimy matrix with polysaccharides, proteins, DNA, bacteria |
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biofilm and immunity |
WBC can't penetrate biofilms |
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biofilms and antibiotics |
antibiotics are ineffective against bacteria living in biofilms |
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bacterial culture: how to grow bacteria in the lab |
need nutrient material (solid, semi-solid, or liquid) nutrient medium should be sterile to start with |
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bacterial culture: agar |
complex polysaccharide from algae for solid structure matrix- looks like gelatin often add animal blood (sheep, horse) for nutrients |
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bacterial culture: colonies |
bacteria grow in colonies- piles of bacteria where the original bacterial was placed on the surface of the agar plate |
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bacterial culture |
use broth or semi-solid growth media, like agar with added nutrients and/or selective agents i.e. chemicals/ antimicrobials different formulations used for culture of different bacteria |
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bacterial culture and human pathogens |
complex media is often used for most human pathogens ex. blood, chocolate agar- which is heated blood that turns brown. blood is denatured |
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bacterial culture: hemolysis |
breakdown of blood cells in agar plates used for presumptive bacterial identification of some bacterial species |
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bacterial culture: hemolysis alpha |
partial breakdown of RBC around and under colony. greening due to methemoglobin |
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bacterial culture: hemolysis beta |
total breakdown of RBC around and under colony, caused by streptolysin S and O creates a clearing around the colony |
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bacterial culture: hemolysis gamma |
no breakdown of RBC around or under colony no growth or change |
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bacterial culture selective media |
supress growth of unwanted bacteria and support growth of desired bacteria helps us find pathogens |
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bacterial culture differential media |
ingredients in media allow us to tentatively identify bacteria, at least into major groups most bacteria wil grow |
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MacConkey plate |
example of selective of differential agar inhibits growth of Gram + and contains lactose to differentiate between lactose fermenting and non-fermenting Gram negatives |
