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LAB! Bio230 Gram Staining

Terms in this set (57)

According to the text book...
1. staining helps make a lasting.....
2. staining bacteria enhances the contrast between...
3. staining permits observation of...
1. staining helps make a lasting preparation
2. staining bacteria enhances contrast btw bacteria and surroundings
3. staining permits observation of greater detail/resolution compared to other procedures
Aseptic technique is used to do what?

In lab what did we use this for??
procedures used
-to avoid introducing unwanted microbes
-to prevent spreading microbes where they aren't wanted.

in lab we used the inoculating loop to transfer bacteria to the slide to make our smear
According to class notes,
What is the purpose of staining?
adding color dye to specimin helps you get a better view....thus staining

highlight the cells morphology (shape)
Why must a bacteria be stained?
In order to see bacteria with a microscope, it must be stained/dyed; otherwise it will be clear and you can't see it (or its morphology)
before staining bacteria, in order to stain it, you must make a ______?
smear (i.e. thin film of bacteria on a glass slide)

"a sample on a slide that you want to view"
How did I prepare a smear in class?
(5 steps)
1. I cleaned the slide
2. I sterilized inoculation loop in the Bunsen burner, hearing it to redness and letting it cool
3. I transferred bacteria to slide with loop (Bacillus subtilis and E. coli)
4. I allowed it to air dry
5. I heat fixed it by passing slide quickly through flame, smear-side up
Why do you heat fix a smear after it air dries?
Heat fixing:
1. kills bacteria
2. helps adhere cells to the slide
3. makes cells more receptive to dye
What are stains?
What charges do stains have?
Stains are dyes, can be positive/basic or negative/acidic.

(Stains are salts as per the book. Salts composed of a (+) and (-) ion, of which only 1 is colored.)

Pos charge stain (the (+) ion has color) means it is a basic dye (such as crystal violet or safranin)

Neg charge stain (the (-) ion has color) means it is an acidic die (such as eosin, acid fuchsin, nigrosin)
Bacteria typically carry a slight _____ charge, so they attract a _____ dye
Bacteria carry a slight negative charge, so they attract a basic dye (the dye itself carries a positive charge).

bacteria is pH 7 and is slightly acidic and thus has a slight (-) charge on cell surface, it will attract a basic (+) dye to it.
Most stains used in lab carry what charge?
most stains used in lab are basic, and thus carry a positive charge.
Which type of stain stains the background, but not the cell itself
a negative stain uses acidic dies that do not stain the cell; stains the background
_____ dye with a ____ charge will stain a negatively charged cell
basic dye, with a pos charge, will stain the negative charged cell.
What are the two main categories of stain techniques?
Compare them
Simple stain techniques:
1. uses 1 basic dye
2. provides basic info about cell shape/arrangement (ex, is there flagella?)

Differential stain techniques:
1. uses more than 1 dye
2. these procedures react differently with diff bacteria; helps distinguish btw diff kinds of bacteria.
differential stain:
1. How many different types of dye are used?
2. What does this help distinguish?
3. What is the most common and important differential stain?
1. How many diff types of dye are used? more than one...they react diff with diff bacteria.
2. This helps distinguish btw diff kinds of bacteria.
3. The most common/imp differential stain is a GRAM stain which classifies bacteria into two large groups, gram positive and gram negative.
If your doc wants to do a stain technique to test your sputum to see what bacteria is causing your URI what would they do?
gram stain because it is a differential stain that can help distinguish btw diff kinds of bacteria.
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