who developed the gram stains
Hans Christian Gram
what are the two categories that John Christian Gram’s Gram stain differentiated?
gram positive (retain purple due to thick peptidoglycan cell wall layer)
gram negative (have outer membrane, lipo-polysaccharide layer, thin layer of peptidoglycan that allows to repel and get rid of the crystal violet and retain the safranin which gives cell pink color)
why do the gram + and gram - cells stain differently
due to the difference in size of the peptidoglycan cell wall
what is the primary stain in the gram stain process?
crystal violet
dyes all cells purple
what does D1 water stand for
Deionized water
how long does the crystal violet stain in the gram stain last for?
1 minute
what does the mordant - grams iodine that is supposed to set for one minute do
locks crystal violet into peptidoglycan for both gram + and gram -
what were the two organisms heat fixed in the gram stain ?
esterichia coli
staphilocacus aureus
decolorizer is important in the gram stain process because this step [..] between the bacteria; remove crystal violet from gram [..] cells
differentiates
negative
the decolorizer should be poured in a steady [..]
stream
what is the secondary stain in the gram stain process>
safranin (1 min)
to stain the colorless gram negative cells pink (doesn’t affect the gram positive cells purple
for the gram stain blot and view the microorganism at [..]x with […]
1000x
oil
if we don’t decolorize for long enough, risk not removing crystal violet from cells so will be false positive or if add too much decolorizer, bleach crystal out to give false negative
yes
what type of bacteria is mycobacterium smegmatis
gram positive rod
what is the acid fast stain used to identify
organisms in the mycobacterium genus
what is the name of the wax layer in a mycobacterium organism
mycolic acid
(specific external coating to cell wall)
why is heat fixation used in mycobacterium smegmatis in the acid fast staining process
to melt the wax layer and allow for penetration
in the acid fast staining process the stain [..] blue is added for 1 minute
methylene blue
in the acid fast staining process carbon fuchsin with heat is done for [..] minutes
5
why is mycobacterium, gram positive rods, difficult to see under the basic gram stain?
because of the wax coating , mycolic acid, repelling water
for the acid fast stain blot, view @ [..]x TM, with [..]
1000
oil
what is a difference between the basic gram stain and the acid fast stain
the grams stains are able to go down the sink while acid fast stains can not.
why must we use the hood when completing the carbon fusion in the acid fast staining process?
carbol fusion is very volatile, the hood will get rid of strong bad smells
the blood agar gives a visual representation of what an organism has or doesn’t have
yes
