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46 Cards in this Set

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a toxin secreted by bacteria that produces a wide range of symptoms
Describe characteristics of Clostridum botulinum: (3)
1. confined to wound site since it does not grow well in body
2. releases and exotoxin that can spread beyond the site of infection and cause neurological disease and death
3. Grows very well in improperly prepared food
Describe characteristics of Clostridum perfringens: (3)
1. Produces an exotoxin called enterotoxin
2. Toxin rarely does severe harm
3. Toxin aids in the spread of the organism by inducing diarrhea and expulsion of the bacterium in the form of spores.
What is the Type III secretory system?
Organelle of virulence seen in Gram (-) bacteria that transports (through many different Type III secretory apparati) virulence factors to host cells via DIRECT INJECTION
Describe how the Type III secretory system works:
The system adheres to the surface of a eukaryotic cell and injects proteins bacterial proteins across the two bacterial membranes and the eukaryotic cell to change the physiology of the target cell.
Function of proteins injected by the Type III secretory apparati? (4)
1. some act of the cytoskeleton or intracellular-signalling cascades of target cells
2. some can serve as membrane receptors for the docking of the bacterium itself at the surface of the cell.
3. some proteins are injected into the macrophages to facilitate phagocytosis
4. some block fusion of the target cell with other cells (ex. proteins injected into the phagosome block fusion with lysosomes)
What is a lysosome? Wiki
An organelle that contains digestive enzymes (acid hydrolases) to digest macromolecules.
What is a phagosome? How does it relate to lysosomes?
a vacuole formed around a particle absorbed by phagocytosis. The vacuole is formed by the fusion of the cell membrane around the particle. A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested. Phagosomes fuse with lysosomes in their maturation process.
What cell culture technique is the most fundamental method of analyzing bacteria that allows many pathogens to be IDed?
Pure culture method
How does the pure culture technique's results allow many pathogens to be IDed?
By looking at the different colony morphologies created in the culture you can ID what kind of bacteria you have.
What are the four phases of bacteria growth?
1. lag phase
2. exponential phase
3. stationary phase
4. death phase
What is happening during the lag phase of bacterial growth?
Bacteria are adapting themselves to growth conditions. Individual bacteria are maturing and not yet able to divide. No growth is occurring!
What is happening during the exponential phase of bacterial growth?
The bacteria grow exponentially, using up the nutrients in their surroundings (growth is dependant on the amount of nutrients).
What is happening during the stationary phase of bacterial growth?
The number of bacterial cells is constant since nutrients will have been depleted and toxic products have accumulated.
What happens in the death phase of bacterial growth?
Number of bacterial cells decreases as nutrients for the cells run out.
What is binary fission?
A form of asexual reproduction used by most prokaryotes to reproduce. This process results in the reproduction of a living cell by division into two near equal parts.
An example of a bacteria that must use binary fission to divide?
E. Coli
What two things are needed for binary fission to happen successfully?
1. need adequate synthesis of new cellular components
2. cellular components must be segregated correctly to produce two functional cells
How is binary fission targeted in pharmacotherapeutics?
Drugs can destroy the pathogen if they can effect the mechanisms of the synthesis of cell components during binary fission.
Prior to binary fission several types of molecules must be made prior to cell division. Name three things that need to be made:
1. nucleic acids for DNA
2. proteins
3. peptidoglycan
What is DNA gyrase?
A PROKARYOTIC enzyme that works just ahead of replication to relax supercoils in the DNA allowing replication to continue. Since it is only in prokaryotes it an excellent target for antibotics.
How is DNA gyrase an effective target to inhibit binary fission?
Since DNA must be replicated in preparation for binary fission a great way to stop the fission is to stop replication. DNA gyrase works in replication by helping make sure DNA polymerase has uncoiled DNA to replicate off of.
What two types of drugs inhibit DNA gyrase?
Antibotics: Novobiocin and Quinolones
Other than targeting DNA replication, how else is binary fission inhibited? (thus aiding in the killing of bacteria)
Since successful binary fission requires protein synthesis ribosomes are an excellent target of antibotics.
What four large groups of antibiotics target ribosomes?
Erythromyocin, tetracyclines, streptomycin, and spectinomycin.
Explain transcription and translational coupling:
In bacteria transcription and translation occur simultaneously. During mRNA synthesis by polymerase, the incompletely transcribed mRNA strand is bound by a ribosome and translation begins even before the polymerase has finished the synthesis of the mRNA strand.
How does protein synthesis occur?
Using a ribosome (a complex molecular machine composed of RNA and protein), amino acids are joined together in a chain according to instructions provided by mRNA.
Function of peptidoglycan in bacteria? When it is made?
Forms bacterial cell wall (made just prior to binary fission)
Peptidoglycan synthesis occurs in three separate compartments in the cell (just prior to binary fission). Explain the three comparment's components:
1. peptidoglycan subunits are synthesized in the cytoplasm
2. these subunits are transferred across the membrane by a carrier molecule
3. the newly transferred subunits are crosslinked to the peptidoglycan already present on the other side of the membrane.
What component of peptidoglycan synthesis is absolutely impairative to the proper growth of the cell?
The making and breaking of crosslinkages (new peptidoglycan subunits to old) by penicillin-binding proteins during peptidoglycan maturation

How does penicillin work?
It works by inhibiting penicillin-binding proteins used to make and break crosslinkages during peptidoglycan maturation
What three things can a pathogen's requirement for energy production tell us as clinicians?
Tell us:
1. the environment the pathogen best survives in
2. where infections are most likely to occur
3. what pathogen we are dealing with (identification)
Nutrient needed by pathogens enter cell to be converted into usable energy. What are three ways bacteria get nutrients from the outside into their cells?
Three ways are:
1. facilitated diffusion (ATP used with gradient)
2. active transport (ATP used agains gradient)
3. Siderophores - molecules secreted by bacteria that trap iron and transport it into the bacterium.
What does bacteria use iron for?
Cell growth
Where are most siderophore genes found?
On plasmids making the plasmids virulence factors. Also find in regular chromosomal DNA.
Why is respiration or fermentation needed in bacterial cells?
Both are used to convert nutrients for the bacteria into energy.
How does respiration convert nutrients into energy?
this process involves a stepwise removal of energy to create a proton gradient across bacterial membrane (eukaryotes: across mito membrane). This gradient is used as the energy source to power transport of molecules into the cell and rotation of the flagellum (etc...)
How are drugs used to inhibit the benefits of respiration in bacterial cells?
Drugs that can damage the cell's envelope destroy the proton gradient formed from respiration and kill the cell.
Describe the process of bacterial fermentation? Compare to respiration
Means of anaerobic removal of energy that causes the production of large amount of organic molecules. The process of fermentation is less efficient than respiration.
How is fermentation used to diagnose an infection?
The organic molecules produced by fermentation have criteria specific to infecting organisms. See organic molecules = know what it infecting the cell
Function of oxygen in bacterial metabolism? Problems?
Oxygen is required for respiration but forms toxic radicals that the bacterial cell must be able to remove. Hydrogen peroxide is removed by peroxidases so that it doesn't damage the cell.
If peroxidases are present in the cell, can hydrogen peroxide be used as an antimicrobial reagent?
The clinical use of H2O2 overwhelms the peroxidases the bacteria has and is an effective antimicrobial reagent.
Regulon? MedDic
In eukaryotes, a genetic unit consisting of a noncontiguous group of genes under the control of a single regulator gene. In bacteria, regulons are global regulatory systems involved in the interplay of pleiotropic regulatory domains and consist of several OPERONS.
What do environmental conditions that bacteria are exposed to induce?
They cause the bacteria to induce regulons that result in an adaptive protective response
Name three adaptive responses bacteria have to environmental conditions:
1. form spores (Bacillia and Clostridia) - these are made in response to lack of nutrients and are a dormant resistant cells
2. engage a heat shock response - produces protective factors allowing cells to survive in high heat and other stresses
3. SOS system response - system repairs DNA damage when mutagenic conditions are encountered

What process is critical to bacterial adaptation?
Gene regulation!