Microbiology Lab practical Flashcards
What type of light activates photolyase?
Visible light
What type of light do pyrimidine dimers result from?
UV light
What is the process called where DNA is repaired by light?
Photoreactivation
What are MSA plates selective and differential for?
Selective-For Gram + halophils
Differential-for organisms that ferment manitol
What does it mean if a bacteria grows on an MSA plate and it turns the media yellow?
The bacteria is a gram + halophile that ferments manitol.
What do the colors of MSA mean?
Red-No manitol
Yellow-Yes manitol.
What is MacConkey broth differential and selective for?
Selective for gram -
Differential for lactose fermentation
What does it mean if you add bacteria to MacConkey broth and the bacteria grows but the media remains purple?
The bacteria is gram -, but doesn’t ferment lactose
What if the bacteria grows and the media turns yellow
It is gram - and ferments lactose.
What quantifies a single culture?
It must have single colonies of the same size.
What is the correct order and timing of a gram stain?
Crystal violet-1min
iodine-1min
ethanol-3 to 5 seconds
safranin-45sec
What are the two results of KOH tests and what do they mean?
Stringy=gram-
No change=gram+
What does a catalase test indicate?
Bubbles=catalase +
No bubbles=catalase-
What are the shapes of the bacteria?
Coccus: Ball
Bacillus: Rod shaped
Spirllium: sprials
What do the different examples on a sheeps blood agar indicate?
No color = no hemolysis
Brown/slight halo = partial hemolysis
Yellow/large halo = complete hemolysis.
