Pathogen picked up during brief contact with a contaminated reservoir
generally non pathogens that are constantly present on skin
minimizes the chances of contamination
the distance between the specimen and the objective lens
objective lens x ocular lens
1 of main functions of microscope, improving the clarity of the image
Microscope which allows light rays to pass directly from the light source through various other components of the microscope to the observers eye
remains in focus after objective lens is changed from low to high power
characteristic of microscope design that allows changing objective lenses without significant change in position of center of field of view.
place you hold on to when carrying the microscope. Supports the body tube.
a small platform on a microscope where the specimen is mounted for examination
located at the bottom of the microscope used for support
gathers the light and passes it through the specimen
Microscope Light Source
to supply light to slide
Regulates the amount of light on the specimen
Microscope Stage Clips
holds slide in place
Individual lens attached to the revolving nose piece
a group of cells which a rises from a single cell
new cultures from isolated colonies
Steak Plate Method
common method for isolating bacteria from a mixed culture
passing slide through flame, affix the bacteria to the slide
only one dye used
a stain of the bacteria itself
stain the background, NEVER heat fix a negative stain
media used in culturing
test tubes containing solid medium that has been allowed to solidify at an angle and the surface of the agar is used for the maintenance of stock cultures of microorganisms, used fro long term bacteria storage 3mo or longer,
isolation technique using a series of serial dilutions to separate CFUs, mixed with liquid agar which then solidifies
a simple stain that stains the bacteria
repelled from bacteria. Background in stained. Negative stains usually have a negative charge which is repelled by the negatively charged proteins on the surface of bacteria. Note: a negative stain does not mean a gram negative.
used in direct stain, green
used in direct stain, purple
used in direct stain, red/pink
Staining procedure which causes cells to stain differently based on properties of the cell wall
has four steps. 1. Primary stain: crystalline violet that stains all bacteria purple 2. mordant: Gram's iodine sets the stain 3. decolorizer: ethanol washes out the stain from gram negative bacteria only 4. counterstain: safranin stains gram negative bacteria pink
A thin protective structure loosely bound to the cell wall that protects the cell against drying, helps trap nutrients, and sometimes binds cells together
A sticky layer that surrounds the cell wall of some prokaryotes, protecting the cell surface and sometimes helping to glue the cell to surfaces.
A general term that includes slime layer and capsule
a thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions
Under harsh environmental conditions, such as loss of a nutritional requirement, bacteria can convert from a vegetative state to THIS or a spore. THIS allows the bacteria to exist in "suspended animation"
spore coat, Keratin like proteins
used to stain small group of organisim that do not readily take up stain, the cell walls of these bacteria contains high concentrations of lipids, perventing uptake of dyes
Ways to prevent contamination
flame loop, inverted postition of plate, hand washing, work near bunsen burner, hold slant caps while removing sample, flame rim of slant...
Precautions used with microscope
make sure microscope is off before plug in, always start with lowest objective, carry with two hands, never use coarse adj for 40x or higher, clean lens after use of oil...
condenser should be as high, iris diaphragm should be open, immersion oil used at 100x
grows yellow in color
grows red in color
What is purpose of streak method?
"thin out" bacterial growth in successive sectors of a plate until individual colonies are obtained
What are the sources of contamination when transferring bacteria?
Not flaming loop, Not working near flame, touching loop to any contaminated surface while cooling
What is the purpose of heat fixing?
1. kills the bacteria 2. makes them adhere to the slide 3. coagulates their protein for better staining.
What is the primary function of the capsule?
Eliminates waste, prevents dehydration, less vulnerable to phagocytosis
What factors determine composition of a capsule?
Environment and the type of nutrients in which the bacterium is growing
What staining techniques are combined in the capsule stain?
direct staining and negative staining
Microorganism used in the capsule stain in lab?
Do you heat fix a capsule stain?
NO, because it is a negative stain
What is the genera of bacteria that have endospores?
Bacillus and Clostridium
Two methods used to stain endospores
Schaeffer-Fulton and Dorner Method
What genus of bacteria exhibit acid fast characteristics?
Mycobacterium tuberculosis, tuberculosis and Mycobacterium leprae, leprosy