Ch.3 Microscopy And Staining Flashcards
(27 cards)
Defined the term microscopy
Do use of a microscope
What is the basic unit of measurement in microbiology what is the size range of most bacteria
Micrometer between 0.2 and 1.0 µm
How do you determine the total magnification of for a microscope
Objective lens x the ocular lens equals the total magnification
Define resolution what are the factors that affect resolution
The ability of lens to distinguish 2 points resolving power shorter wavelengths of light provide a greater resolution
Why is it necessary to use immersion oil to 10 the best results with the microscope define refractive index
It is is to keep light from bending before it enters the objective lens
refractive index is the light bending ability of a medium for example air has different refractive index compared to oil
Bright field
Dark objects are visible against a bright background
Dark field
Light objects against dark background
Phase contrast
Used for viewing internal structures of cells in natural state
Florescence
Uses UV light to view cells stained with flurochromes
Confocal
Uses laser light and produces 3-D image
Differential interference contrast
Accentuates light diffraction and uses 2 light beams
Electron microscopy
Used to see virus is not useful for observing living cells because it requires a thinly sliced section and there’s too high of energy
Identify the uses of each type of electron microscopy
TEM transmission electron microscope stand with heavy metal salt use is thin slices
SEM Scanning electron microscope beam of electrons the skin whole specimen
Scanning probe microscopy
Can see DNA is this metal prologue to scan specimen
Define staining
Consist of positive and negative Ion
Base dye cat ion positive Acidic die anion negative
How are smears prepared
Thin film of microbes heat fixed onto a slide
Give an example of basic an acidic die and explain how they interact with bacteria to produce a stain
Basic days basic fusion crystal violet malachite green methanol blue safranin die goes into cell
Acidic days acidic fusion eosin Rose Bengal, nigrosin repelled by negative charge of cell wall Creating a negative stain
How are negative stains prepared
For what application is this type of stain especially useful for
Using a acidic die - repels with negative charge cell wall staining background
More accurate for size and to see the capsule better which is the outside bubble
What is the primary purpose of a simple stain
Help determine shape size and arrangement use basic die cat ion that is attracted to the cell wall
What is a differential staying
Example Graham and acid-fast stains specific type of stand that allows for microbe identification and distinguishing between cells and I mixed sample
Describe the steps of the gram staining procedure
After shmear is made and heat fixed apply primary stain Crystal violet add iodine which binds crystal violet and traps in the cell then use rapid decolorization with ethanol or acetone for 10 seconds counter stand with saffron se then blot
What is a mordant used for in Gram stain
Iodine is used to fix the crystal violet to the bacterial cell wall
In a correct Gram stain what is the color of gram-positive cells and Graham negative cells
Gram-positive is purple Graham negative is red
What is the relationship between cell wall structure and the Gram stain
Gram-positive thick cell wall monoderm inside and small
Graham negative thin cell wall surrounded by two diderms more resistant to antibodies because of an impenetrable wall
