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60 terms

MB Lab 1231 Exam 1

STUDY
PLAY
Transient Microorganism
Pathogen picked up during brief contact with a contaminated reservoir
Resident Microorganism
generally non pathogens that are constantly present on skin
Aseptic Techinque
minimizes the chances of contamination
Working Distance
the distance between the specimen and the objective lens
Total Magnification
objective lens x ocular lens
Resolution
1 of main functions of microscope, improving the clarity of the image
Brightfield Microscope
Microscope which allows light rays to pass directly from the light source through various other components of the microscope to the observers eye
Parfocal
remains in focus after objective lens is changed from low to high power
Parcenter
characteristic of microscope design that allows changing objective lenses without significant change in position of center of field of view.
Microscope Ocular
eyepiece
Microscope Arm
place you hold on to when carrying the microscope. Supports the body tube.
Microscope Stage
a small platform on a microscope where the specimen is mounted for examination
Microscope Base
located at the bottom of the microscope used for support
Microscope Condenser
gathers the light and passes it through the specimen
Microscope Light Source
to supply light to slide
Microscope Diaphragm
Regulates the amount of light on the specimen
Microscope Stage Clips
holds slide in place
Microscope Objectives
Individual lens attached to the revolving nose piece
Colony
a group of cells which a rises from a single cell
Subculturing
new cultures from isolated colonies
Steak Plate Method
common method for isolating bacteria from a mixed culture
Heat Fix
passing slide through flame, affix the bacteria to the slide
Simple Stain
only one dye used
Direct Stain
a stain of the bacteria itself
Negative Stain
stain the background, NEVER heat fix a negative stain
Agar
media used in culturing
Slants
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,
Pour Plates
isolation technique using a series of serial dilutions to separate CFUs, mixed with liquid agar which then solidifies
Direct Stain
a simple stain that stains the bacteria
Negative Stain
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.
Methylene Blue
used in direct stain, green
Crystal Voilet
used in direct stain, purple
Safranin
used in direct stain, red/pink
Congo Red
negative stain
Nigrosin
negative stain
Differential Staining
Staining procedure which causes cells to stain differently based on properties of the cell wall
Gram Stain
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
Slime Layer
A thin protective structure loosely bound to the cell wall that protects the cell against drying, helps trap nutrients, and sometimes binds cells together
Capsule
A sticky layer that surrounds the cell wall of some prokaryotes, protecting the cell surface and sometimes helping to glue the cell to surfaces.
Glycocalyx
A general term that includes slime layer and capsule
Endospore
a thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions
Dormant State
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"
Cystine
spore coat, Keratin like proteins
Acid Fast
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...
Best resolution
condenser should be as high, iris diaphragm should be open, immersion oil used at 100x
M. luteus
grows yellow in color
M. roseus
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?
Klebsiella Pneumoniae
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