Gram Staining

During gram staining, gram POSITIVES come out ______ and gram NEGATIVES come out ______.

purple, pink

The part of the cell envelope that determines the color seen during Gram staining is called what?

cell wall

What are the basic steps (or chemicals used) during Gram staining?

1) Crystal Violet 2) Gram’s Iodine 3) Decolorization 4) Safranin (red dye)

The first step (adding Crystal violet) of gram staining is the _______ stain where both gram negative and positive cells take in the dye through cell walls turning ______.

primary, purple

The second step (adding Gram Iodine) of Gram staining acts as a ________ allowing the Crystal violet to stick to the cell walls of both the gram negative and gram positive cells.

mordant

The third step and most critical (Decolorization) is taking an ______ solvent like alcohol or acetone to ____ the cell wall of the purple dye color for a few seconds.

organic, strip

After ______________ is where we see the difference between gram - and gram + bacteria; since gram positives have a thick cell wall they are still purple while gram negatives are colorless due to thin, puny cell walls.

decolorization

The fourth and final step of decolorization is applying the ______ ____ (Safranin: red dye) that is red or pinkish in color which is masked by the violet purple in gram + bacteria and stains the gram - red following colorlessness.

counter, stain

Gram stain is often the _____ step used to figure out what unknown species you are looking at.

first

Some bacteria are _____ - _____________: cells that do not come out as clearly pink or purple in gram staining

gram indeterminant

One example of a gram - indeterminant is __________; they have a cell wall that is NOT made of peptidoglycan so it does not stain with gram stain (just a bacteria thing)

Archaea

Another gram - indeterminant is called a ______________: lacks a cell wall entirely

mycoplasma

Mycoplasmas, since they do not have a cell wall, tend to be __________: can alter shape and size due to change in environment.

pleomorphic

What two bacteria have unique types of lipids in their cell membrane making them gram - indeterminant?

1) Mycobacterium 2) Nocardia