Simple Staining Flashcards
What’s the purpose of staining bacteria?
To make their shape and grouping more visible.
What shape is Staphylococcus epidermis?
A spherical-shaped (coccus) bacteria.
What shape is Citrobacter freundii?
A rod-shaped bacteria
What shape is Spirillum volutans?
A spiral-shaped bacterium that forms volutin granules.
What’s the purpose of heat fixing slides?
To make the organisms stick to the glass slide. If they aren’t fixed to the slide they easily wash off,
What charge do cell surfaces have?
Negative cell surface generally.
Are basic dyes or acidic dyes better for staining bacteria? Why?
Basic dyes, because basic dyes carry a positive charge so they are attracted to the negative cell surface.
On the flip side acidic dyes carry negative charge, which is repelled by the cell surface.
Why is it crucial to let you slide dry after washing off the dye?
If water droplets remain, they will get suspended in place by the oil immersion step, distorting the image.
What is the purpose of immersion oil?
To prevent refraction(bending of light rays), as they pass from the slide to the air to then back into glass of the lens.
Why do we want to eliminate refraction?
It provides the highest possible resolution of image.
Define Resolution in Microbiology.
The ability to distinguish closely-spaced objects as being separate entities.
Are coverslips needed for simple staining?
No, because it’s not a wet mount, and that’s generally the only time we use coverslips.
After a simple staining, do we need to boil the slide in order to reuse it?
No, because the fixing and staining process kills all the cells, so you do not need to boil the slide before washing.
How do you know when you’ve cleaned off all the oil from the 100x lens?
If a new piece of lens paper does NOT acquire any sort of shine or transparency after rubbing the lens.
