Lab Practical Review Flashcards
Blood agar-
Result: area ajacent to bacteria appears green when held up to light?
alpha hemolytic bacteria
hemolysins destroyed RBC’s
Blood agar-
Result: Area adjacent to bacteria appears clear when help up to light
Beta-hemolytic bacteria
Hemolysins were able to partially destroy RBC’s
Blood agar-
Result: Area adjacent to bacteria appears red
Gamma-hemolytic bacteria
No hemolysins were released
Phenylethyl Alchohol Agar
Result: Growth looks same as TSA
Gram positive
Cell wall remains intact
Phenylethyl Alchohol Agar
Result: No growth/less than on TSA
Gram-negative
Cell wall destroyed
Mannitol Salt agar-
Result: Growth and color change of media
S. aureus
Sugar in agar has been fermented which results in color change
Mannitol Salt agar-
Result: Growth and no color change
Any other staphylococci bacteria
Sugar in media hasnt been fermented
MacConkey agar-
Result: Growth, colonies are red/pink
Gram-negative, Lac +
Lactose in media has been fermented which changes the ph and results in color change
MacConkey agar-
Growth, colonies are white/colorless/golden/brown
Gram-neg, Lac -
Lactose in media has no been fermented
MacConkey agar-
No growth
Gram positive
Eosin-methyline blue agar-
Growth, colonies are purple-black (sometimes with a dark center)
Gram-neg, Lac +
Same as MacConkey
Lactose in media has been fermented which changes the ph and results in color change
Eosin-methyline blue agar-
Growth, colonies has metallic green color
Gram-neg, Lac +
E.coli
Eosin-methyline blue agar-
growth, colonies are colorless
Gram-neg, Lac -
Lactose in media has no been fermented
Eosin-methyline blue agar-
No growth
Gram positive
Starch Hydrolysis
After addition of iodine, blue black color in innoculation zone
Negative result
Starch is still present
Starch Hydrolysis
Colorless are in innoculation zone
Positive
Starch has been broken down
Lipid Hydrolysis-
Innoculation zone is opaque/cloudy
negative result
Lipids are still present
Lipid Hydrolysis-
Innoculation zone is clear
Postive
Lipids have been broken down
Casein Hydrolysis-
Innoculation zone is opaque/cloudy
Negative
Casein is still present
Casein Hydrolysis-
Inocculation zone is clear
Positive
Casein has been broken down
Gelatin Hydrolysis-
Medium remains solid
Negative
Gelatin is still present
Gelatin Hydrolysis-
Medium has liquidified
Positive
Gelatin has been broken down
Agar is?
a chemical derived from seaweed that solidifies into a jellylike semisolid
What is a medium?
a liquid gel designed to support bacterial/cell growth
Why do you innoculate near the Busen burner?
Creates a vaccum near plates so microbes in the air done contaminate the swab/loop
What is a subculture?
transfer of a microbe from one medium to another
What is a pureculture?
Culture containing bacteria from only one strain
An obligate areobe needs?
oxygen to survive
What are the 4 objectives on the microscobe?
4x, 10x, 40x, and 100x
Oil changes the _________________ of the light.
refractory pattern
An electron microscope uses a _____________ to illuminate a specimen and produce a magnified image.
Refractory pattern
B. cereus is a?
common cause of food posioning
P. vulgaris is?
a common cause of UTI and wound infections
P. Aeruginosa is?
Cause of infections & sepsis but can cause death if found in longs or kidneys
Wet mount resuluts- Bacterium Motility Morphology B. cereus P. Vulgaris P. Aeruginosa
Wet mount resuluts-
Bacterium Motility Morphology
B. cereus True motility rod
P. Vulgaris Brownian Mov. rod/bacillis
P. Aeruginosa true motility cocco bacillus `
What is brownian movement?
Appearance of movement, but really just molecules bombarding the bacteria
Why do we incubate the plates at 37 degrees C and then 4?
Because 37 degrees C is the temp of the human body and will allow bacteria to grow and reproduce, then incubation is at 4 degrees to preserve
Simple staining can be used to identify more than the morphological characteristics of microorganisms.
T/F
False
What are the 3 main categories of bacteria shapes
Rod, Cocci, Spiral
What does every staining technique start with?
a bacterial smear
What are the two types of dyes for a bacterial smear?
methaline blue, crystal violet
A gram stain is a type of ______________.
differential staining
The primary stain is?
Used to stain all cells on the slide
The decolorizing step is used for?
removing the stain for different types of cells
The counter stain is used for?
staining newly decolorized cells but has no effect on cells holding primary stain
The gram stain reaction is based on the amount of _________ found in the cell walls of bacteria.
peptidogylcan
Gram ___________ cells many layers of peptidoglycab in their cell walls.
positive
Gram ________ cells have one layer of peptidogylcan in their cell walls.
one layer
What is the agent used for the primary stain in a gram stain?
What color would Gram +/- be?
crystal violet
-both purple at this stage
What is the agent used for the mordant/fixative and what color will gram +/- be?
iodine
both still purple
What agent is used for decolorizing?
What color will the gram +/- be?
alchohol
Gram + =purple
Gram-= clear
What agent is used for the counter stain?
What color will gram + /- be?
Safranin
Gram + =purple
Gram - =red/pink
Gram + / -?
B. cereus
Gram +
Gram + / -?
S. aureus
Gram +
Gram + / -?
E. coli?
Gram -
Bacterial growth occurs via?
binary fission
What occurs during binary fission?
Gather nutrients
Duplicates nucleic acids and proteins
Splits into two daughter cells/clones of itself
Which bacterial phase are bacteria acclimating to their new enviroment and getting ready for cell division?
lag phase
Which bacterial phase are bacterial cells duplicating at a constant rate and are metabolically active?
Log phase
What bacterial phase are bacterial cells experiencing cell death and cell growth simulataniously and toxic waste products are generated in large amounts?
Stationary phase