Explain why negative staining involves acidic dyes. Give an example of an acidic dye
uses acidic/anionic dye because its (-)charge is repelled by the (-) charge on the outside of the cell staining the background not the microbe/cell. Nigrosin
Which type of microscopy is most likley used to observe stained cells?
Bright field microscopy
How are electron microscopy and light microscopy different?
electron microscopes use a beam of electrons instead of a beam of light. Electrons have a shorter wavelength than visible light. Higher resolution than light
What is one way fluorescence microscopy is used for?
By labeling specific molecules or organelles with fluorescent markers, researchers can track their movement, localization, and interactions in living cells.
What is a special stain? Name the 3 special stains in the slides and explain what they are used for
capsule stain, endospore stain and flagella stain...
What is used as the mordant in gram staining and what does it do?
The mordant is Gram's Iodine. This binds to the crystal violet making a large complex that adheres to the peptidoglycan cell wall.
What are viruses typically measured in?
nanometers
Why is fixing necessary for most staining procedures?
helps preserve morphology, ensures the little beasties will not run off or be washed off the slide
What microscope would you use to view the mitochondrial structure of a protozoan
phase-contrast, fluorescence, TEM
What is the purpose of simple staining?
Observe the morphology, shape/arrangement of cells.
how are brightfield, darkfield, phase-contrast, and fluorescence microscopy similar?
They all need a light source
how do acid fast negative bacteria appear after preforming an acid fast stain
no mycolic acids in cell wall so unable to retain carbolfuschin after decolorizing step. instead take up the counterstain (methylene blue) and appear blue
What microscope would use to view specimens 200nm to 10mm
light microscopes
What microscope would you use to view a ribosome
TEM
Explain how the phase-contrast microscope works and what we use it for
Brings direct and reflected or diffracted light rays together to form an image of the specimen on the ocular lens. used for detailed observation of living cell
differentiate gram staining and endospore staining
They both use 2 stains to differentiate microbes; differentiates between Gram(+)(-) appear purple/pink; endospore stain visulaizes endospore green in pink cell
List Gram stain steps, and describe the appearance of gram-positive and gram-negative cells after each step.